code: protected Collection<String> getKeys() {
  		Collection<String> result = Collections.emptySet();
  		if (_moduleBuilds != null) {
  			result = Collections.unmodifiableCollection(_moduleBuilds.keySet());
  		}
  		return result;
  	}
docs: /*
  Returns the set of keys for cached entries. Used for unit testing
  
  @return the cache keys