CharsRef has confusing methods/needs tests/bugs [LUCENE-3277]

[asfimport]

While looking at #4306, i noticed a few things:

• lots of internal methods (e.g. copy) use grow(). I don't think they should do this. CharsRef should work like BytesRef, i don't think it needs to be a stringbuffer. i think its ok to expose a public grow() method like we did for bytesref though.
• the append() method is totally confusing, and doesnt make sense compared to BytesRef, copy() might also have issues.
• a lot of these methods are unused, we should at least add tests for them, or remove ones we don't need.

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Migrated from LUCENE-3277 by Robert Muir (@rmuir), updated Nov 01 2011

[asfimport]

Robert Muir (@rmuir) (migrated from JIRA)

the same grow() issue happens in IntsRef.copy and LongsRef.copy.

I think we should fix this, and in general, i think these guys should have consistent APIs.

[asfimport]

Robert Muir (@rmuir) (migrated from JIRA)

#4622 addresses the confusing append() issue.

[gsmiller]

I came across a reference to this issue while working on #12305. It looks like the CharsRef family is pretty consistent with BytesRef now (including the builders). I don't see anything outstanding here, and was going to close this out, but wanted to check with @rmuir first to make sure I'm not missing something. Thanks.