code: public ServletOperation getOperation(SlingHttpServletRequest request, Method method) {
          ServletOperation operation = null;
          E extension = RequestUtil.getExtension(request, defaultExtension);
          Map<E, O> extensionDefaults = operationDefaults.get(method);
          if (extensionDefaults != null) {
              O defaultOperation = extensionDefaults.get(extension);
              if (defaultOperation != null) {
                  Map<E, Map<O, ServletOperation>> extensions = operationMap.get(method);
                  if (extensions != null) {
                      Map<O, ServletOperation> operations = extensions.get(extension);
                      if (operations != null) {
                          operation = operations.get(RequestUtil.getSelector(request, defaultOperation));
                      }
                  }
              }
          }
          return operation;
      }
docs: Retrieves the servlet operation requested for the used HTTP method.
  Looks in the selectors for a operation and gives their implementation in the extensions context.
  
  @param request the servlet request
  @param method  the requested HTTP method
  @return the operation or 'null', if the requested combination of selector
  and extension has no implementation for the given HTTP method