code: public static SoyType computeLowestCommonType(
        SoyTypeRegistry typeRegistry, Collection<SoyType> types) {
      SoyType result = null;
      for (SoyType type : types) {
        result = (result == null) ? type : computeLowestCommonType(typeRegistry, result, type);
      }
      return result;
    }
docs: Compute the most specific type that is assignable from all types within a collection.
  
  @param typeRegistry Type registry.
  @param types List of types.
  @return A type that is assignable from all of the listed types.