code: public <T> boolean registerPojo(Class<T> typeClass, Schema<T> schema)
      {
          assert typeClass != null && schema != null;
          
          final HasSchema<?> last = pojoMapping.putIfAbsent(typeClass.getName(), 
                  new Registered<T>(schema));
          
          return last == null || (last instanceof Registered<?> && 
                  ((Registered<?>)last).schema == schema);
      }
docs: Registers a pojo.
  Returns true if registration is successful or if the same exact schema
  was previously registered.
  Used by {@link RuntimeSchema#register(Class, Schema)}.