public static String getInternalLevelName(String external)
          throws IllegalArgumentException{
    String refinedAlias = external.trim().toUpperCase();
    for (String [] pair : LEVEL_ALIASES) {
      if (pair[ALIAS_COLUMN].equals(refinedAlias)) {
        return pair[INTERNAL_NAME_COLUMN];
      }
    }
    String message = String.format("Unknown operation level %s", external);
    throw new IllegalArgumentException(message);
  }
Converts external operation level alias to an internal name
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/RequestOperationLevel.java