mybatis的if标签判断子类属性-There is no getter for property named 'export' in

 <select id="findList" resultType="BndExport">

         SELECT

             <include refid="bndExportColumns"/>

         FROM bnd_export a

         <include refid="bndExportJoins"/>

         <where>

             a.del_flag = #{DEL_FLAG_NORMAL}

             <if test="createDate != null and createDate != ''">

                 AND a.create_date = #{createDate}

             </if>

             <if test="createDateStart!=null and createDateStart!='' and createDateEnd!=null and createDateEnd!=''">

                 AND a.create_date between to_date('${createDateStart}','yyyy-mm-dd hh24:mi:ss') and to_date('${createDateEnd}','yyyy-mm-dd hh24:mi:ss')

             </if>

             <if test="company != null and company != ''">

                 AND a.company = #{company}

             </if>

17             <if test="bndExportFreight != null and bndExportFreight != '' and bndExportFreight.vessel != null and bndExportFreight.vessel != ''">

                 AND b.vessel= #{bndExportFreight.vessel}

             </if>

             <if test="bndExportFreight != null and bndExportFreight != '' and bndExportFreight.voyage != null and bndExportFreight.voyage != ''">

                 AND b.vessel= #{bndExportFreight.voyage}

             </if>

         </where>