protected static String getStringValue(Map<?, ?> map, String key) {
    Object value = getValue(map, key);
    return (value == null) ? null : value.toString();
  }
Safely retrieves the requested value (converted to a String) from the supplied Map
<p/>
The found value will be converted to a String using the {@link Object#toString()} method.

@param map a Map containing the relevant data
@param key a String declaring the item to retrieve
@return a String representing the requested data; or null if not found
ambari-server/src/main/java/org/apache/ambari/server/state/kerberos/AbstractKerberosDescriptor.java