As the JavaDoc states, DateFormats are inherently unsafe for multithreaded use. The detector has found a call to an instance of DateFormat that has been obtained via a static field. This looks suspicous.
For more information on this see Sun Bug #6231579 and Sun Bug #6178997.
Obs (lines 1014, 1106, etc.), PatientProgramItem, MigrationHelper, FormUtil.
Eliminate all errors reported by Sonar for this rule: