Suppress "Unlikely argument type for equals()" warnings in tests

Suppress "Unlikely argument type for equals()" warnings in tests

This new warning was introduced in Eclipse 4.7 Oxygen [1].

The only instances of the warning are in test code that is asserting
that some class does not compare equal to Strings. As in the Gerrit
project [2] these asserts are arguably overkill, but arguably also
a reasonable test of an equals implementation. Ignore the warning in
these cases.

Note that if the project is opened in an earlier version of Eclipse,
a warning "Unsupported @SuppressWarnings" will be emitted.

[1] https://www.eclipse.org/eclipse/news/4.7/M6/
[2] https://gerrit-review.googlesource.com/#/c/gerrit/+/110339/

Change-Id: I08ea33d71e6009cf0f37e6492a475931f447256b
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>