public static PdxInstance fromJSON(String jsonString, String... identityFields) {
    return new JSONFormatter().toPdxInstance(jsonString, identityFields);
  }
Converts a String JSON document into a PdxInstance

@param jsonString The JSON String to convert to PDX
@param identityFields Any desired identity fields on the JSON object to be used for equals and
       hashCode computations
@throws JSONFormatterException if unable to create the PdxInstance
@return The PdxInstance
geode-core/src/main/java/org/apache/geode/pdx/JSONFormatter.java