private static String erasedToString(TypeMirror type) {
    return ERASED_STRING_TYPE_VISITOR.visit(type);
  }
An equivalent to {@link CompilationRule} that uses ecj (the Eclipse compiler) instead of javac.
If the parameterized test is not selecting ecj then this rule has no effect.
common/src/test/java/com/google/auto/common/OverridesTest.java