public SelectorConditionDTOBuilder operator(final String operator) {
            this.operator = operator;
            return this;
        }
Sets the {@code operator} and returns a reference to this Builder enabling method chaining.

@param operator the {@code operator} to set
@return a reference to this Builder
shenyu-admin/src/main/java/org/apache/shenyu/admin/model/dto/SelectorConditionDTO.java