code: public DynamoDBQueryExpression<T> withQueryFilterEntry(String attributeName, Condition condition) {
          if (queryFilter == null) {
              queryFilter = new HashMap<String,Condition>();
          }
          queryFilter.put(attributeName, condition);
          return this;
      }
docs: Adds a new condition to the the query filter.
  <p>Returns a pointer to this object for method-chaining.
  
  @param attributeName
  The name of the attribute on which the specified condition
  operates.
  @param condition
  The filter condition applied on the attribute.