private static String getCommandParameterValue(Map<String, String> commandParameters, String propertyName) {
    return ((commandParameters == null) || (propertyName == null)) ? null : commandParameters.get(propertyName);
  }
Gets a property from the given commandParameters

@param commandParameters map of command parameters
@param propertyName      property name to find value for
@return value of given proeprty name, would return <code>null</code>
if the provided commandParameters is null or  if the requested property is not found
in commandParams
ambari-server/src/main/java/org/apache/ambari/server/serveraction/kerberos/UpdateKerberosConfigsServerAction.java