I have solved the Bug 3086444. Now Squirrel use the previous defined custom date formates after restarting.
After reading the properties the dateFormat was not initialized with the saved values.
I have added a TestCase for verification.
Patch for Bug 3086444: Use custom dateFormat after restart
Committed to SVN. Applied equivalent fixes to Timestamp and Time types.
The test case that was submitted was causing another test case to fail (DataTypeTimeTest), when run together in the same JVM (maven). I combined the test cases from the class submitted into the original DataTypeTimeTest and fixed the issue with running them in the same JVM.
When I said DataTypeTimeTest, I actually meant DataTypeDateTest.