Add FilterFieldType

[msfroh]

Description

This class allows developers (in core or plugins) to wrap an existing field type, delegating all behavior by default, overriding specific methods as needed.

See linked issue for more details.

Related Issues

Resolves #17624

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 5180b1a: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[kkewwei]

It make sense to me. But it seems not delegate all methods, such as fielddataBuilder. Also it seems don't solve the problem mentioned in #17575, it need the indexedValueForSearch, only if we also support FilterTermBasedFieldType?

[bzhangam]

indexedValueForSearch

indexedValueForSearch will not be directly invoked to process query. It will be invoked through function like termQuery. Since we delegate the termQuery it will use the implementation of indexedValueForSearch of the delegate.

[msfroh]

It make sense to me. But it seems not delegate all methods, such as fielddataBuilder. Also it seems don't solve the problem mentioned in #17575, it need the indexedValueForSearch, only if we also support FilterTermBasedFieldType?

In #17575, it doesn't actually need indexedValueForSearch, since that's internal to the implementation of the delegated field type (since that's a helper used by the various *Query methods).

You're absolutely right about fielddataBuilder -- not sure how I missed that, since I tried overriding all methods from MappedFieldType. I intentionally avoided implementing typeName(), because I believe that the filtered field type should have its own type name.

I'll add a unit test that uses reflection to enforce overrides of all methods to catch mistakes if anyone adds more methods to MappedFieldType.

[navneet1v]

Please add java docs on this class, with some examples on how to use it. This is a good addition in core.

[navneet1v]

should we annotate this with @publicapi?

[github-actions]

❌ Gradle check result for bcd79b6: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?