private String getClusterName(Map<String, Object> properties) throws IllegalArgumentException {
    if (properties.get(CREDENTIAL_CLUSTER_NAME_PROPERTY_ID) == null) {
      throw new IllegalArgumentException("Property " + CREDENTIAL_CLUSTER_NAME_PROPERTY_ID + " must be provided");
    } else {
      return String.valueOf(properties.get(CREDENTIAL_CLUSTER_NAME_PROPERTY_ID));
    }
  }
Retrieves the <code>Credential/cluster_name</code> property from the property map

@param properties a map of properties
@return the cluster name
@throws IllegalArgumentException if <code>Credential/cluster_name</code> is not in the map or
                                 <code>null</code>
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/CredentialResourceProvider.java