No completion documentation for source methods with parameters

[tsmaeder]

When invoking completion for a method defined in the same class, the completion UI never shows documentation when the method has a parameter (or more). The same thing works for methods without parameters.
This can be reoproduced with both Che and VSCode

[tsmaeder]

To reproduce:

1. create the following class:

public class Foo {

    public static void main(String[] args) {
	    // write your code here
	    System.out.println("Hello World!");
	    
    }
    
    /**
     * This method has Javadoc
     */
    public static void foo(String bar) {
        
    }

    /**
     * This one does, too.
     */
    public static void bar() {

    }
}

2. Put the cursor on empty line after the println
3. invoke code assist
4. move the menu highlight to "bar()".
5. observer: you see the method javadoc
6. now move the menu highlight to "foo(String bar)"
7. observer: you do not see the Javadoc for "foo".

[tsmaeder]

The problem seem to lie with CompletionResolveHandler#resolve(...). On line 114, "method.exists()" returns false for methods with parameters.

[fbricon]

Most likely, we don't translate the parameters properly around https://github.com/eclipse/eclipse.jdt.ls/blob/master/org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/CompletionResolveHandler.java#L107, so no matching method is found.