Added support for empty field arrays in mappings

[cfontes]

Fix for #6133, added the ability to send empty arrays as part of an index mapping json. For single and multi field properties objects

Sorry for the import changes, IntelliJ doesn't like eclipse imports and fights it like the devil.

If the test are in a non standard format please advise. I just find them easier to read like this.

[jpountz]

I think we should not just ignore when something else than a map is provided? Maybe we could do something like:

} else if (propName.equals("fields") {
  final Map<String, Object> multiFieldsPropNodes;
  if (propNode instance of List && ((List<?>) propNode.isEmpty()) {
    multiFieldsPropNodes = Collections.emptyMap();
  } else if (propNode instanceof Map) {
    multiFieldsPropNodes = (Map<String, Object>) propNode;
  } else {
    throw new MapperParsingException("Expected map for property [fields] on field [" + multiFieldName + "] or [" + type + "] but got a " + propNode.getClass());
  }
}

[jpountz]

@cfontes I left two comments on the PR but otherwise it looks good, especially the tests.

I would be nice to fix these imports. I'm quite surprised that you mention that you use Intellij since I thought we were using Intellij's defaults (we even have an eclipse configuration to make sure we are using Intellij's import style). Or maybe you have a non-default configuration of imports in Intellij?

Could you please also sign our contributor license agreement so that we can eventually merge this pull request?

Thanks!

[jpountz]

Could you please also sign our contributor license agreement so that we can eventually merge this pull request?

I just learned that it is in, so it is allright for the CLA.

[cfontes]

Thanks for the review.

I will look into fixing those and push it asap.

About the imports, you are right... it's my bad, one of my other projects have a very specific rule for imports and it got into my ES project by mistake. Will fix that too.

Cheers!

[cfontes]

@jpountz

Added back the IntelliJ default import settings.
Added some code to validate the scenarios explained.
Added some tests to validate those.

Since there is nothing really to do in parseProperties when the parameter is an empty List it just skip the parsing and proceed without any exception since now it's a valid input that does nothing. If it's anything else (besides a map) it throws an exception. Please take a look to see if it's OK like that for you.

Thanks!

[jpountz]

Merged, thanks!