attempt to fix buffer underflow

- IMap#get usually returns clone of original value,
  but when the type is byte[], it returns the original value.
- During the deserialization process, Kryo temporarily modifies the input buffer,
  which may cause problem when multiple threads were reading the same value.

- applying clone only to value deserialization for now,
  since it is unlikely that caller will be modifying Map key

Change-Id: I52214ba711b4060663b0e1c451f49bdd1d472ea9
1 file changed