code: protected boolean isInternalDebug() {
          if (internalDebug == null) {
              synchronized (ScriptingExpression.class) {
                  if (internalDebug == null) {
                      // almost no cost but cache just in case 
                      internalDebug = LastaDiProperties.getInstance().isInternalDebug();
                  }
              }
          }
          return internalDebug;
      }
docs: ============