code: public Set<String> getSupportedOptions() {
          SupportedOptions so = this.getClass().getAnnotation(SupportedOptions.class);
          if  (so == null)
              return Collections.emptySet();
          else
              return arrayToSet(so.value(), false);
      }
docs: If the processor class is annotated with {@link
  SupportedOptions}, return an unmodifiable set with the same set
  of strings as the annotation.  If the class is not so
  annotated, an empty set is returned.
  
  @return the options recognized by this processor, or an empty
  set if none