RFE code assist: Start completing after only :: in streams while determinig the class from the stream.

Excuse my bad english!

When coding streams, code assist should start at :: without writing the classname, while determining the class from the stream.

Example
ArrayList<String> example = new ArrayList<>();

At now, code assist is only available after writing the classname:

example.stream().filter(String::

But it can allready starts here, while determinig and completing the class from the stream without the need to write the classname:

example.stream().filter(::

This makes it much easier, especially für long classnames.

Start from the issue's stream example and inspect the Java code-assist handling for incomplete method references. Determine where completion after :: is processed and how the stream element type is inferred. Done means example.stream().filter(:: offers relevant String completions without requiring the class name.