This is ready for review.

This is very great work. Congrats!

Please note that addOnPageChangeListener is a "new" method. Previously only setOnPageChangeListener was present. So you have to check that which method is available, and use setOnPageChangeListener if addOnPageChangeListener is not present.

Also you should validate that ViewPager class is present or not.

We definitely should add functional test for this. You should check out the SeekBar test for example. AFAIK there is not way to access the listener in ViewPager directly or though a shadow class in Robolectric, so you should retrieve it by reflection (using FEST-Reflect).

We also did not have the feature that finding the parameter by the name. I think we should not use that. Instead, we should define an order of the parameters when finding the parameter by type is ambiguous.

That way you could also use our simple ValidatorParameterHelper API. See an example here. You should also use that on all new annotation validations in this PR.

For finding the method exist or not, do you have any sample case for this?
Validating if ViewPager is present or not seems not that hard. It will be like this.

getProcessingEnvironment().getElementUtils().getTypeElement(CanonicalNameConstants.VIEW_PAGER) != null;

I'll take a look SeekBar for functional tests.

ValidatorParameterHelper looks nice! Let me use that.

For @PageScrolled, this would be the candidate order of parameters. ViewPager is the first parameter and rest is onPageScrolled parameter order.

        validatorHelper.param.inOrder() //
                .type(CanonicalNameConstants.VIEW_PAGER).optional() //
                .primitiveOrWrapper(TypeKind.INT).optional() //
                .primitiveOrWrapper(TypeKind.FLOAT).optional() //
                .primitiveOrWrapper(TypeKind.INT).optional() //
                .validate((ExecutableElement) element, validation);

What do you think?

For checking a method is avaible, you can use similar code to this.

The rest is okay!

You are fast! Thanks for your help.

Now, it ready for reviewing, again.

I will go to trip a few days where I am not available for the Internet. Until I will come back from there, could you wait for merging? I will squash commits.

Thanks.

LGTM in general, i added some comments. Thanks!

Thanks! I will fix then as soon as I come back.

Fixed it. It's ready for review, again.

Looks good to me. Please squash the commits and i can merge.

Squashed

Thanks, great PR! Would you mind updating the wiki as well?

No problem! I will let you know as soon as I update wiki.