Rule S6212: Local-Variable Type Inference (var) should be used

The idea is to start simple: report only when the type on the LHS is exactly the same as the one on the RHS.

MyClass myClass = new MyClass(); // Noncompliant
var myClass = new MyClass(); // Compliant
List<String> list = new ArrayList<String>(); // Compliant, not the same type.
var list = new ArrayList<String>(); // Compliant

Be careful to only report an issue if the code is supporting Java 10 and if the variable is local.

Eventually, in a second step, we could improve the rule when the type is not the same (subtype).