[Java] [Spring Client] Add an exception provider interface to allow for exception redefinition

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700

[Mattias-Sehlstedt]

I have scenarios where I want to have more fine-grained control over the exceptions that an ApiClient can throw. This so that I can handle them more properly by distinguishing them by type and decorating messages. Doing this with the current structure is cumbersome since the same exceptions are redefined in several places, and they are strongly coupled to the enormous ApiClient.mustache. So I have to customize the base mustache to adjust this behavior.

In order to decouple the exception handling and provider better control over it, I suggest that it is extracted into an ExceptionProvider. This retains the current behavior of the exceptions thrown currently, but it also provides an extension point where these can be easily configured as a separate concept. Either with the ExceptionProvider.mustache, or by injecting an extended interface into the ApiClient.

This approach is currently tailored towards Spring's RestClient and WebClient only. RestTemplate is intentionally omitted, since it is deprecated.

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package || exit
  ./bin/generate-samples.sh ./bin/configs/*.yaml || exit
  ./bin/utils/export_docs_generators.sh || exit
  

  (For Windows users, please run the script in WSL)
  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  IMPORTANT: Do NOT purge/delete any folders/files (e.g. tests) when regenerating the samples as manually written tests may be removed.
• File the PR against the correct branch: master (upcoming 7.x.0 minor release - breaking changes with fallbacks), 8.0.x (breaking changes without fallbacks)
• If your PR solves a reported issue, reference it using GitHub's linking syntax (e.g., having "fixes #123" present in the PR description)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

cc @bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

---

Summary by cubic

Adds an ExceptionProvider interface for Spring RestClient and WebClient clients so users can redefine thrown exceptions without editing ApiClient.mustache. Default behavior is unchanged and exception handling is now decoupled and injectable.

• New Features

  • Generate ExceptionProvider.java from ExceptionProvider.mustache for webclient and restclient.
  • Add exceptionProvider field with getter/setter in generated ApiClient; defaults to ExceptionProvider.DEFAULT.
  • Update JavaClientCodegen to include the supporting file for these libraries.

• Migration

  • No changes needed; defaults preserve current exceptions.
  • To customize: implement ExceptionProvider and call apiClient.setExceptionProvider(...).
  • Applies to Spring RestClient and WebClient only; RestTemplate is not included.

^{Written for commit 49ecd01. Summary will update on new commits.}

[cubic-dev-ai]

7 issues found across 70 files

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[wing328]

thanks for the PR

is this change backward compatible?

[Mattias-Sehlstedt]

From an exception-type point of view it is non-breaking. And given that the client re-generates all classes for the library then they should just see a new class that is necessary to add in order for the ApiClient to work as previously.

I will investigate how previous changes regarding adding additional generated classes have been conducted to verify that there is no extra conditions that are to be considered. This to make sure that there are no odd clients that have allow-listed file generation or similar that might be impacted differently.

[Mattias-Sehlstedt]

Previous changes that have added additional support classes have not mentioned anything about considering whether current user might generate them or not. So I do not believe that is an issue that should occur. E.g., #4998 and #20700