4117: Added Md5String() method and updated tests.

[andrey-qlogic]

Fixes#4117

[andrey-qlogic]

@frankyn, would you please take a look at this PR.

[frankyn]

@andrey-qlogic adding this feature to the client sg. I recommend adding the same for crc32c as well.

[andrey-qlogic]

Added Crc32cString() method and updated tests. Added to snippets.

[frankyn]

Hi @andrey-qlogic, Thanks for the update. I chatted with the GCS team about this design. It sounds good to them but suggested adding a Hex Hash String to GCS base64 encoded string for setCrc32c() method to the Blob class.

The naming convention would help: @googleapis/yoshi-java do you have input on Java community method names?

WDYT about the following names?

getMd5ToHexString()
setMd5FromHexString()
getCrc32cToHexString()
setCrc32cFromHexString()

[andrey-qlogic]

Renamed new methods using naming convention getMd5ToHexString(), getCrc32cToHexString().
I believe that setter methods are not required as those new methods return a string representation md5 and cr32 that set in another methods.

[frankyn]

The other method setMd5 for example expects the base64 encoded string of an Md5 hash. It would be nice to have a similar helper method to getting the md5 hash as a base64 decoded md5 hex string.

[andrey-qlogic]

@frankyn, that is unclear, are you suggesting to add a new setter method to class BuilderImpl
like
public Builder setMd5FromHexString(String md5HexString)
that will do something like
byte[] decoded = BaseEncoding.base64().decode(md5HexString);

and assign it to md5 ?

Otherwise the method getMd5ToHexString is implepented for BlobInfo class in 85588a3

I would appreciate for your input

[frankyn]

I'm expecting to see public Builder setMd5FromHexString(String md5HexString) do the following:

// pseudo codesetMd5FromHexString(Stringmd5HexString) {
// convert md5HexString back to its binary representation e.g. reverse binary to human readable hex.// base64 encode the binary representation// set the value of Md5 in BlobInfo to the base64 encoded version.
}

[andrey-qlogic]

Added methods to set Md2 and Crc32s from hex strings.

[andrey-qlogic]

there are code format issues that will be fixed with #4437

[andrey-qlogic]

@frankyn, I realized that Md5 sometimes used with 0x prefix that can be easily removed at BlobInfo class.

[frankyn]

For this PR, @andrey-qlogic could you skip supporting the removal of "0x" for now?
I'm leaning towards supporting that incrementally instead of in the first iteration.

Thank you, apologies for constant delays on these reviews.

[andrey-qlogic]

@frankyn, do you want me to drop the whole last commit 7f19e33 ?

[frankyn]

Yes except the integration test.

[andrey-qlogic]

Reverted back the commit 7f19e33 except integration tests.

[andrey-qlogic]

@frankyn, do you mean the change for both Md5 and Crc32c, correct
What about unit tests values?

google-cloud-java/google-cloud-clients/google-cloud-storage/src/test/java/com/google/cloud/storage/BlobInfoTest.java

Line 55 in 7de46b4

privatestaticfinalStringMD5 = "0xFF00";

[andrey-qlogic]

@frankyn
Removed code that removes 0x from hex string.
Removed code that adds prepending 0x.
Removed OmitPadding, it looks like it is not required.
Added MD_NO_PREFIX, CRC32C_NO_PREFIX constant for testing.

[frankyn]

I think this is the last nits. Thanks for your patience @andrey-qlogic.

[andrey-qlogic]

@frankyn , I realized that new BigInteger(md5HexString, 16).toByteArray() is not safe with leading zeros. I changed to DatatypeConverter.parseHexBinary(md5HexString). It works fine. If needed we can make an utility method instead.

[frankyn]

LGTM, I notice you dropped, DatatypeConverter.parseHexBinary(md5HexString) due to supportability. Thanks for verifying that!

[andrey-qlogic]

thanks for the approval