docs: public static void enableCategories(Category... categories) throws IOException {
          if (s_tracer == null) {
              start();
          }
          final VoltTrace tracer = s_tracer;
          assert tracer != null;
  
          final ImmutableSet.Builder<Category> builder = ImmutableSet.builder();
          builder.addAll(tracer.m_enabledCategories);
          builder.addAll(Arrays.asList(categories));
          tracer.m_enabledCategories = builder.build();
      }