Description

FilterIndexInput and FilterIndexOutput do not always delegate calls to the instances that they decorate which can cause them to override the behavior of the instances they are delegating to.
For example, it is possible in your own IndexInput implementation to override readMapOfStrings but if an instance of your classe is decorated by a FilterIndexInput instance when readMapOfStrings is called the logic that will be called is the one of DataInput.readMapOfStrings.
This behavior is verified by the TestFilterIndexInput.testOverrides unit test.
This approach seems error prone to me and go against the implementation of the methods like readMapOfStrings that could have been made final if they should not have been overridden.

Happy to provide a patch if that problem is recognize as such. :-)

Version and environment details

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