Custom retry handlers

[Chris Gillum (cgillum)]

This PR completes the retry policy feature for Java by allowing developers to implement custom retry policies using code. It's intended for use-cases where declarative retry policies aren't flexible enough.

Example syntax

TaskOptionsoptionsWithRetryHandler = TaskOptions.FromRetryHandler(retryCtx -> {
// Retries MyException or any sub-class of MyExceptionif (retryCtx.getLastFailure().isCausedBy(MyException.class)) {
returntrue;
} else {
// For any other exception type, retry up to 4 timesreturnretryCtx.getLastAttemptNumber() < 5;
} });
TaskOrchestration = ctx -> {
ctx.callActivity("MyFlakeyActivity1", null, optionsWithRetryHandler).get();
ctx.callActivity("MyFlakeyActivity2", null, optionsWithRetryHandler).get();
};

Code changes:

• New public classes to support custom retry logic
• Refactored integration tests to share common logic
• Added support for non-retriable errors
• Fixed bug with backoff coefficient

Resolves#18

[kaibocai (kaibocai)]

LGTM!

[David Justo (davidmrdavid)]

Left some comments, but overall looks pretty much ready to me. Just waiting to read responses to my comments before approving. In any case, I see now how the shim-less approach enables RetryHandles for OOProc. Exciting!

[David Justo (davidmrdavid)]