A DESCRIPTION OF THE REQUEST :
Now we have 3 constants for java.nio.charset.CodingErrorAction:
IGNORE
REPLACE
REPORT
I propose to have 3 more:
IGNORE_PROGRESSIVE
REPLACE_PROGRESSIVE
REPORT_PROGRESSIVE

Alternative:
*_ADVANCING

Additionally:
*_CONSERVATIVE or *_PROTECTIVE as redundant copy of the just existing.

JUSTIFICATION :
There was a discussion about, which length a malformed coder result should return. See:
- http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6762515
- http://mail.openjdk.java.net/pipermail/core-libs-dev/2008-September/000695.html

With the 3 additional CodingErrorAction developer would have both possibilities.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
E.g. in case of byte sequence of length 3 where 3rd byte is corrupted:
   IGNORE --> skip 1 byte in source buffer
   REPLACE --> insert replacement in destination buffer and advance 1 byte in source buffer
   REPORT --> report length 1 by malformed coder result
   IGNORE_PROGRESSIVE --> skip 3 byte in source buffer
   REPLACE_PROGRESSIVE --> insert replacement in destination buffer and advance 3 byte in source buffer
   REPORT_PROGRESSIVE --> report length 3 by malformed coder result

... in case of byte sequence which has start byte for 3 bytes where 2nd byte is corrupted:
   normal action: --> treat as malformed sequence of length 1.
   progressive action: --> treat as malformed sequence of length 2.

ACTUAL -
Only 1st 3 variants are offered, but not always strict, see 3rd actual result on http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6795537


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For easy implementation of my proposal, method CharsetDecoder#decodeLoop() should always return the "progressive" values.
Method CharsetDecoder#decode() should transpose to "conservative" values if requested
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