code: public void add(ServiceReference<D> declarationSRef) {
          D declaration = getDeclaration(declarationSRef);
          boolean matchFilter = declarationFilter.matches(declaration.getMetadata());
          declarations.put(declarationSRef, matchFilter);
      }
docs: Add the declarationSRef to the DeclarationsManager.
  Calculate the matching of the Declaration with the DeclarationFilter of the
  Linker.
  
  @param declarationSRef the ServiceReference<D> of the Declaration