tree 92c6fccc1aa30e614c3c9bfcefb1e594ebf3a6b2
parent 68a7bd53d3c5a19c93fcc0c9031a01f5e82f92a8
author David Pursehouse <dpursehouse@collab.net> 1559370445 +0900
committer David Pursehouse <dpursehouse@collab.net> 1559370445 +0900

Revision: Add helper method for comparison to Revision.NULL

When Error Prone checks are enabled, comparing to Revision.NULL
with the == or != operator results in a warning:

  [ReferenceEquality] Comparison using reference equality instead of value equality

The NULL instance is used as a sentinel, so comparing with reference
equality is correct.

Rather than suppressing the warning at every place in the code, add
a helper method that can be used, and suppress the warning only there.

Note that the "ReferenceEquality" warning is Error Prone specific and
suppressing it results in an "Unsupported @SuppressWarnings" warning.

Change-Id: Ia50404f76f88c405b9298a645760c019384c92ff