private Set<? extends Element> getElements(Class<? extends Annotation> a) {
        return roundEnv.getElementsAnnotatedWith(a);
    }
{@code AbstractQuerydslProcessor} is the base class for Querydsl annotation processors and
contains the main processing logic. The subclasses just provide the configuration.

@author tiwe
querydsl-apt/src/main/java/com/querydsl/apt/AbstractQuerydslProcessor.java