code: @Override
      public Builder notBefore(long time_from) throws InvalidClaimException {
  
          if (time_from > 0) {
              claims.put(Claims.NOT_BEFORE, time_from);
          } else {
              String err = Tr.formatMessage(tc, "JWT_INVALID_TIME_CLAIM_ERR", new Object[] { Claims.NOT_BEFORE });
              throw new InvalidClaimException(err);
          }
          return this;
      }
docs: /*
  (non-Javadoc)
  
  @see com.ibm.ws.security.jwt.internal.Builder#notBefore(long)