Improve `UseDiamondOperator` suggestion with actual type

[Luro02]

The current message is a generic one that seems to be difficult to understand:

The types specified in the '< A, B, ... >' can be remove, use '<>' instead.

A better one would be

Explicit type argument String can be replaced with <>

for the code

List<String> value = new ArrayList<String>();

The problem

The check is tricky to implement, hence it is implemented by PMD. There exists an issue #559 for rewriting it in spoon, but is hardly worth the effort (you would have to reimplement java type-inference).

The PMD message only includes the changed type and not the original one: Explicit type arguments can be replaced by a diamond: 'new p.Generic<>()'

The solution

• It might be possible to resolve the position to its type: RuleViolation#getLocation seems to contain information about not only the line, but also about its column.
• Resolve it based on the message by finding the referenced type in the source code. E.g. find which spoon element corresponds to new p.Generic<>() and has an explicit type in <>
• Use the line to infer the type where <> can be simplified. (might not work for multiple simplifications in the same line or source code that spans multiple lines?)