SQL generator may use non-reproducible order in rare cases #527

The SnippetTiebreaker comparator can return a premature result if one Snippet or both being compared has a null implementor name, which can result in an output ordering that depends on the sequence of comparisons performed.

The case is unlikely to be seen in practice, as an implementor name can only be made null by explicit implementor="" in an annotation or -Addr.implementor=- when invoking the Java compiler.

Nonetheless, the tiebreaker method can be made more simple and obviously correct by taking advantage of the Java 8 additions to Comparator.