private int setEnvironmentVariableHelper(String name, String value) {
    if (processEnvironmentVariable(name, value)) {
      envVars.put(name, value);
      return 0;
    } else {
      return -2;
    }
  }
Subclasses can override this method if they want to accept environment variables
with unknown names. When an executor is not able to go through all the valid configurations
it can use this method as a temporary workaround.
@return true if environment variables with unknown names are acceptable. This method returns false by default.
samza-sql-shell/src/main/java/org/apache/samza/sql/client/interfaces/EnvironmentVariableHandlerImpl.java