public static ClientAuth fromPropertyValue(String prop) {
      if (prop == null || prop.length() == 0) {
        return NEED;
      }
      return ClientAuth.valueOf(prop.toUpperCase());
    }
Converts a property value to a ClientAuth enum. If the input string is empty or null, returns
<code>ClientAuth.NEED</code>.
@param prop the property string.
@return the ClientAuth.
@throws IllegalArgumentException if the property value is not "NONE", "WANT", "NEED", or
                                 empty/null.
hbase-common/src/main/java/org/apache/hadoop/hbase/io/crypto/tls/X509Util.java