DefaultSyncContextTest contains duplicate test

Some test methods in DefaultSyncContextTests are the same when compared line-by-line:

• testCreateValueFromBytesArray, testCreateValueFromBinary and testCreateValueFromInputStream;
• testGetIdentityRefSyncGroup and testGetIdentityRefSyncUser.

If these methods are actually testing different things because of a lucky state of the instance variable and an even luckier running order, they should be reworked to be independent. Otherwise, some of them should be removed.