The class DiagnosticFormatter has some problems:

*) A single class is in charge for providing both raw format (-XdrawDiagnostics option) and standard format
*) All the formatting logic is accomplished by a single formatter method format(JCDiagnostic)

Those problems makes it very difficult to extend DiagnosticFormatter in order to provide more specific formatting capabilities:

*) Any subclass of DiagnosticFormatter must preserve the raw format. Such format is exploited in locale-independent regression tests, so that any minimal change to the raw format will cause a lot of regression failures.

*) It's not possible to redefine specific parts of the formatter's behavior (e.g. change the way in which the formatter renders a diagnostic's location) without redefining the whole formatting logic

Please, refactor the DiagnosticFormatter class.