This information is available via Javassist, so this would be a change to the ClassFactory service.
This is especially important since TAPESTRY-1341, since a lot of service builder methods, even within the same module, will be called "build" (with various parameters).
Came out sweet.
This also encompasses reporting of failures on component event handler methods: either failures to provide parameters to the method, or methods returning incorrect type values. These too are now identified with the file name and line number (though the exception report page can not, alas, display the Java source the way it can component template source).