Lambda used as ArgumentMatcher causes decamelized lambda name to appear in error message

[Marcono1234]

Version

Mockito version: 3.5.13

Description

Relates to #1932

When using a lambda or method reference expression as ArgumentMatcher and the matcher fails, the error message contains the lambda / method reference class name in "decamelized" form which is rather irritating, e.g.:

myInterface.doSomething(
<Mockito test$$ lambda$ 4 8/ 0x 0 0 0 0 0 0 0 8 0 0c 8f 4 4 0>
);

Expected would be that similar to anonymous classes the error output says "<custom argument matcher>". This could probably be achieved by testing for Class.isSynthetic() in org.mockito.internal.matchers.text.MatcherToString.toString(ArgumentMatcher<?>) before calling decamelizeMatcher there.

Test case

public class MockitoTest {
    interface MyInterface {
        void doSomething(String s);
    }
    
    private static boolean matches(String s) {
        return false;
    }
    
    public static void main(String[] args) {
        MyInterface mock = mock(MyInterface.class);
        try {
            verify(mock).doSomething(argThat(arg -> false));
        } catch (Error e) {
            e.printStackTrace();
        }
        try {
            verify(mock).doSomething(argThat(MockitoTest::matches));
        } catch (Error e) {
            e.printStackTrace();
        }
        
        // When an anonymous class is used the output is '<custom argument matcher>'
        // (as expected)
        verify(mock).doSomething(argThat(new ArgumentMatcher<>() {
            @Override
            public boolean matches(String argument) {
                return false;
            }
        }));
    }
}

[mockitoguy]

This could probably be achieved by testing for Class.isSynthetic() in

Sounds like a good idea. Do you want to submit a PR? Thanks!

[Marcono1234]

Sorry for the delay, have submitted the pull request: #2071
Feedback is appreciated!