protected static Object getValue(Map<?, ?> map, String key) {
    return ((map == null) || key == null) ? null : map.get(key);
  }
Safely retrieves the requested value from the supplied Map

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