code: public ELContext setELContext(ELContext context) {
          ELContext prev = elContext;
          elContext = new StandardELContext(context);
          return prev;
      }
docs: Set the ELContext used for parsing and evaluating EL expressions.
  The supplied ELContext will not be modified, except for the context
  object map.
  @param context The new ELContext.
  @return The previous ELContext, null if none.