FULL PRODUCT VERSION :
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Mac OS X 10.9.2
Darwin sethr.local 13.1.0 Darwin Kernel Version 13.1.0: Thu Jan 16 19:40:37 PST 2014; root:xnu-2422.90.20~2/RELEASE_X86_64 x86_64

A DESCRIPTION OF THE PROBLEM :
For JSON with integer keys (that is, strings containing integers), JSON.parse hallucinates nonexistent entries if there are gaps between the keys.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
% jjs
jjs> JSON.stringify(JSON.parse(JSON.stringify({"0":0,"2":2})))
{"0":0,"1":0,"2":2}
jjs> JSON.stringify(JSON.parse(JSON.stringify({"0":"","2":""})))
{"0":"","1":null,"2":""}

Note that the "gap" between 0 and 2 has been filled. The value used depends on the types of the values of the entries.


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I expect the same behavior that V8 and Rhino both give:

V8 version 3.21.17 [sample shell]
> JSON.stringify(JSON.parse(JSON.stringify({"0":0,"2":2})))
{"0":0,"2":2}
> JSON.stringify(JSON.parse(JSON.stringify({"0":"","2":""})))
{"0":"","2":""}

% jrunscript
js> JSON.stringify(JSON.parse(JSON.stringify({"0":0,"2":2})))
{"0":0,"2":2}
js> JSON.stringify(JSON.parse(JSON.stringify({"0":"","2":""})))
{"0":"","2":""}

ACTUAL -
shown in steps to reproduce

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
I'm walking the results of JSON.parse and stripping out key/value pairs where the value is null. (Fortunately my data is such that this is valid.)