code: private IMessageFilter[] getFilter(Method method, Handler subscription) {
          Filter[] filterDefinitions = collectFilters(method, subscription);
          if (filterDefinitions.length == 0) {
              return null;
          }
          IMessageFilter[] filters = new IMessageFilter[filterDefinitions.length];
          int i = 0;
          for (Filter filterDef : filterDefinitions) {
              IMessageFilter filter = filterCache.get(filterDef.value());
              if (filter == null) {
                  try {
                      filter = filterDef.value().newInstance();
                      filterCache.put(filterDef.value(), filter);
                  } catch (Exception e) {
                      throw new RuntimeException(e);// propagate as runtime exception
                  }
              }
              filters[i] = filter;
              i++;
          }
          return filters;
      }
docs: retrieve all instances of filters associated with the given subscription