Give FieldNamingStrategy the ability to return multiple String names

[mfriesen]

Purpose

This pull request enhances the FieldNamingStrategy in Gson to support returning multiple strings for a field name. This behavior aligns with the alternate names functionality provided by the @SerializedName annotation, allowing for greater flexibility in field mapping.

Description

The FieldNamingStrategy interface has been updated to allow implementations to return a list of potential field name mappings. This allows deserialization to succeed if any of the alternate names are present in the JSON data.

The changes include is to modifying the FieldNamingStrategy interface to support returning a collection of names. This allows the FieldNamingStrategy interface to behave like the @SerializedName annotation.

Checklist

• [ X] New code follows the Google Java Style Guide
  This is automatically checked by mvn verify, but can also be checked on its own using mvn spotless:check.
  Style violations can be fixed using mvn spotless:apply; this can be done in a separate commit to verify that it did not cause undesired changes.
• [X ] If necessary, new public API validates arguments, for example rejects null
• [X ] New public API has Javadoc
  • [ X] Javadoc uses @since $next-version$
    ($next-version$ is a special placeholder which is automatically replaced during release)
• [ X] If necessary, new unit tests have been added
  • [ X] Assertions in unit tests use Truth, see existing tests
  • [X ] No JUnit 3 features are used (such as extending class TestCase)
  • [X ] If this pull request fixes a bug, a new test was added for a situation which failed previously and is now fixed
• [X ] mvn clean verify javadoc:jar passes without errors

[Marcono1234]

Thanks for this suggestion! It seems that would resolve #1002

However, we cannot change the return type of translateName from String to List<String> since that would be an incompatible change.
But what might be possible, similar to @SerializedName#alternate, is adding an additional method to FieldNamingStrategy, for example translateToAlternateNames(Field): List<String> (or a better name). The next Gson version will target Java 8, so we could provide a default implementation of this method which returns an empty list. This should preserve backward compatibility.

This is just an idea though, maybe there are other possible approaches.

[mfriesen]

@Marcono1234 Great idea. I wasn't sure what the best approach would be. I'll review your suggestion and see if I can get it to work.

[Marcono1234]

Thanks for the changes!

The build currently fails due to formatting violations. You can solve this by running mvn spotless:apply.

Also note that the commits are squashed on merge here, so you don't have to force-push / rewrite commits, but instead can incrementally make changes to this pull request.

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@eamonnmcmanus what do you think about these proposed changes?

[Marcono1234]

Thanks for your changes! A few more small points, but looks good besides that.

We will however have to wait for the opinion and review from a direct Gson maintainer then.