code: void addSuppressions(Set<String> suppressions) {
      lazyInitInfo();
  
      if (info.suppressions != null) {
        suppressions = Sets.union(suppressions, info.suppressions);
      }
      info.suppressions = ImmutableSet.copyOf(suppressions);
    }
docs: Adds a set of suppressions to the (possibly currently empty) set of suppressions.
  @param suppressions A list of suppressed warning types.