Unfetched attribute access error

Насколько понимаю, подобная проблема уже была ранее описана в этой теме. Но, к сожалению, придумать решения все равно не могу.
Ошибка возникает исключительно при создании новой сущности, если указать атрибут NetworkElement (Ассоциация Many to One).
Сохранение новой [new] сущности без указания данного атрибута происходит без ошибок, дальнейшая работа с атрибутом так же не вызывает ошибок.

Версия платформы 6.7.9

Скрин

Снимок

Трейс + eclipseLink
 2018-02-16 11:07:20.957 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - INSERT INTO ENERSTROYMAIN_ACCOUNTING_POINT (ID, APPARTMENT, ASKUE, BOOK_NUM, CREATE_TS, CREATED_BY, DELETE_TS, DELETED_BY, EX_ACC_NUM, EX_MONTAGE_PLACE, EX_PU_MONTAGE_PLACE, EX_PU_NUM, EX_PU_PHASE, EX_PU_TYPE, EX_SUMM_T, EX_T1, EX_T2, EX_T3, EX_TEL, EX_YEAR, FIZ18, HOME, IN_NETWORK_ELEMENT, IS_UPLOADED_UP, NETWORK_ADRESS, NUM_PU_BILLING, PORT, PPO_COMMENT, PPO_INPUT_AVALAB, PPO_INPUT_LENGTH, PPO_PROP_GP_SSH, PPO_PROP_GP_SVD, PPO_PROP_NUM, SMR_DEL_POINT_TYPE, SMR_GP_SSH, SMR_GP_SVD, SMR_IMPORT_CHANGE, SMR_INPUT_CHANGE, SMR_INPUT_LENGHT, SMR_STAMP_LOCKER, SMR_STAMP_PU, STRUCTURE, SUBSCRIBER, SUBSCRIBER_NUM, TARIF, TEL, UPDATE_TS, UPDATED_BY, VERSION, IMPORT_STAGE_ID, NETWORK_ELEMENT_ID, OBJ_ID, PPO_FEEDER_ID, PPO_INPUT_TYPE_ID, PPO_MONTAGE_PLACE_PU_ID, PPO_PHASE_ID, SMR_ADM_ACT_ID, SMR_LINE_TYPE_ID, SMR_MONTAGE_PLACE_ID, STATUS_ID, STREET_ID, SUBSCRIBER_TYPE_ID, TKO_ID, TP_ID, TP_METER_ID, METER_ID, DTYPE) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
     bind => [cda7098b-4487-41f5-052a-2a50812ed0f3, null, null, null, 2018-02-16 11:07:20.932, admin, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, false, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, null, 2018-02-16 11:07:20.932, null, 1, null, 46dd56f0-c539-0b6f-4ced-f3600671049b, 51d76250-fa04-5533-e74c-01c7a710e8e3, null, null, null, null, null, null, null, null, null, null, null, null, null, null, MKDAccountingPoint]
    2018-02-16 11:07:20.959 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - [2 ms] spent
    2018-02-16 11:07:20.965 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - SELECT t1.ID, t1.DTYPE, t1.APPARTMENT, t1.CREATE_TS, t1.CREATED_BY, t1.DELETE_TS, t1.DELETED_BY, t1.EX_ACC_NUM, t1.EX_MONTAGE_PLACE, t1.EX_PU_MONTAGE_PLACE, t1.EX_PU_NUM, t1.EX_PU_PHASE, t1.EX_PU_TYPE, t1.EX_SUMM_T, t1.EX_T1, t1.EX_T2, t1.EX_T3, t1.EX_TEL, t1.EX_YEAR, t1.FIZ18, t1.HOME, t1.IS_UPLOADED_UP, t1.PPO_COMMENT, t1.PPO_INPUT_AVALAB, t1.PPO_INPUT_LENGTH, t1.PPO_PROP_GP_SSH, t1.PPO_PROP_GP_SVD, t1.PPO_PROP_NUM, t1.SMR_DEL_POINT_TYPE, t1.SMR_GP_SSH, t1.SMR_GP_SVD, t1.SMR_IMPORT_CHANGE, t1.SMR_INPUT_CHANGE, t1.SMR_INPUT_LENGHT, t1.SMR_STAMP_LOCKER, t1.SMR_STAMP_PU, t1.STRUCTURE, t1.SUBSCRIBER, t1.TEL, t1.UPDATE_TS, t1.UPDATED_BY, t1.VERSION, t1.IMPORT_STAGE_ID, t1.OBJ_ID, t1.PPO_FEEDER_ID, t1.PPO_INPUT_TYPE_ID, t1.PPO_MONTAGE_PLACE_PU_ID, t1.PPO_PHASE_ID, t1.SMR_ADM_ACT_ID, t1.SMR_LINE_TYPE_ID, t1.SMR_MONTAGE_PLACE_ID, t1.STATUS_ID, t1.STREET_ID, t1.SUBSCRIBER_TYPE_ID, t1.TP_ID, t1.TP_METER_ID, t1.METER_ID, t1.ASKUE, t1.BOOK_NUM, t1.IN_NETWORK_ELEMENT, t1.NETWORK_ADRESS, t1.NUM_PU_BILLING, t1.PORT, t1.SUBSCRIBER_NUM, t1.TARIF, t1.NETWORK_ELEMENT_ID, t1.TKO_ID, t0.ID, t0.CREATE_TS, t0.CREATED_BY, t0.DELETE_TS, t0.DELETED_BY, t0.STAGE, t0.UPDATE_TS, t0.UPDATED_BY, t0.VERSION, t2.ID, t2.ACC_CLASS, t2.CREATE_TS, t2.CREATED_BY, t2.DELETE_TS, t2.DELETED_BY, t2.IS_USED, t2.MAC, t2.NETWORK_ADRESS, t2.NEXT_VETIFICATION_YEAR, t2.NUMBER_, t2.PHASE, t2.TYPE_, t2.UPDATE_TS, t2.UPDATED_BY, t2.USE_DATE, t2.VERIFICATION_YEAR, t2.VERSION, t2.MANUFACTURER_ID, t3.ID, t3.DTYPE, t3.CREATE_TS, t3.CREATED_BY, t3.DELETE_TS, t3.DELETED_BY, t3.UPDATE_TS, t3.UPDATED_BY, t3.VERSION, t3.CONTRACT_ID, t3.EXECUTOR_ID, t3.LOCALITY_ID, t3.STATUS_ID, t3.HOME, t3.STRUCTURE, t3.TEHNICAL_CODE, t3.STREET_ID, t4.ID, t4.DTYPE, t4.CONTRACT_NAME, t4.CREATE_TS, t4.CREATED_BY, t4.DELETE_TS, t4.DELETED_BY, t4.UPDATE_TS, t4.UPDATED_BY, t4.VERSION, t4.CONTROLLER_ID, t4.OWNER_ID, t4.STATUS_ID, t5.ID, t5.CREATE_TS, t5.CREATED_BY, t5.DELETE_TS, t5.DELETED_BY, t5.NAME, t5.UPDATE_TS, t5.UPDATED_BY, t5.VERSION, t5.PARENT_ID, t6.ID, t6.CREATE_TS, t6.CREATED_BY, t6.DELETE_TS, t6.DELETED_BY, t6.FIAS_ID, t6.LOCALITY_NAME, t6.UPDATE_TS, t6.UPDATED_BY, t6.VERSION, t6.AREA_ID, t6.TYPE_ID, t7.ID, t7.AREA_NAME, t7.CREATE_TS, t7.CREATED_BY, t7.DELETE_TS, t7.DELETED_BY, t7.UPDATE_TS, t7.UPDATED_BY, t7.VERSION, t7.ZONE_ID, t8.ID, t8.CREATE_TS, t8.CREATED_BY, t8.DELETE_TS, t8.DELETED_BY, t8.NAME, t8.UPDATE_TS, t8.UPDATED_BY, t8.VERSION, t9.ID, t9.CODE, t9.CREATE_TS, t9.CREATED_BY, t9.DELETE_TS, t9.DELETED_BY, t9.NAME, t9.UPDATE_TS, t9.UPDATED_BY, t9.VERSION, t9.GROUP_ID, t9.TYPE_ID, t10.ID, t10.CODE, t10.CREATE_TS, t10.CREATED_BY, t10.DELETE_TS, t10.DELETED_BY, t10.NAME, t10.UPDATE_TS, t10.UPDATED_BY, t10.VERSION, t10.STAGE_ID, t11.ID, t11.CREATE_TS, t11.CREATED_BY, t11.DELETE_TS, t11.DELETED_BY, t11.STAGE, t11.UPDATE_TS, t11.UPDATED_BY, t11.VERSION, t12.ID, t12.CREATE_TS, t12.CREATED_BY, t12.DELETE_TS, t12.DELETED_BY, t12.FUSE_LINKS, t12.NUM, t12.UPDATE_TS, t12.UPDATED_BY, t12.VERSION, t12.INPUT_ID, t12.PLACE_NEW_PU_ID, t12.PLACE_NEW_TT_ID, t12.TP_ID, t13.ID, t13.CAPASCITY, t13.CREATE_TS, t13.CREATED_BY, t13.DELETE_TS, t13.DELETED_BY, t13.FUSE_LINKS, t13.NUM, t13.UPDATE_TS, t13.UPDATED_BY, t13.VERSION, t13.VOLTAGE, t13.TP_ID, t14.ID, t14.DTYPE, t14.CAPASCITY, t14.CREATE_TS, t14.CREATED_BY, t14.DELETE_TS, t14.DELETED_BY, t14.GPS_SH, t14.GPS_VD, t14.IS_UPLOADED_UP, t14.NOMINAL_VOLTAGE, t14.NUMBER_, t14.PC, t14.PC_FIDER, t14.UPDATE_TS, t14.UPDATED_BY, t14.VERSION, t14.IMPORT_STAGE_ID, t14.OBJ_ID, t14.STATUS_ID, t14.TYPE_ID, t15.ID, t15.DTYPE, t15.CREATE_TS, t15.CREATED_BY, t15.DELETE_TS, t15.DELETED_BY, t15.UPDATE_TS, t15.UPDATED_BY, t15.VERSION, t15.CONTRACT_ID, t15.EXECUTOR_ID, t15.LOCALITY_ID, t15.STATUS_ID, t15.HOME, t15.STRUCTURE, t15.TEHNICAL_CODE, t15.STREET_ID, t16.ID, t16.DTYPE, t16.CONTRACT_NAME, t16.CREATE_TS, t16.CREATED_BY, t16.DELETE_TS, t16.DELETED_BY, t16.UPDATE_TS, t16.UPDATED_BY, t16.VERSION, t16.CONTROLLER_ID, t16.OWNER_ID, t16.STATUS_ID, t17.ID, t17.CREATE_TS, t17.CREATED_BY, t17.DELETE_TS, t17.DELETED_BY, t17.FIAS_ID, t17.LOCALITY_NAME, t17.UPDATE_TS, t17.UPDATED_BY, t17.VERSION, t17.AREA_ID, t17.TYPE_ID, t18.ID, t18.AREA_NAME, t18.CREATE_TS, t18.CREATED_BY, t18.DELETE_TS, t18.DELETED_BY, t18.UPDATE_TS, t18.UPDATED_BY, t18.VERSION, t18.ZONE_ID, t19.ID, t19.CREATE_TS, t19.CREATED_BY, t19.DELETE_TS, t19.DELETED_BY, t19.NAME, t19.UPDATE_TS, t19.UPDATED_BY, t19.VERSION, t20.ID, t20.CREATE_TS, t20.CREATED_BY, t20.DELETE_TS, t20.DELETED_BY, t20.DESCRIPTION, t20.UPDATE_TS, t20.UPDATED_BY, t20.VERSION, t21.ID, t21.CREATE_TS, t21.CREATED_BY, t21.DELETE_TS, t21.DELETED_BY, t21.DESCRIPTION, t21.MONTAGE_TRUE, t21.UPDATE_TS, t21.UPDATED_BY, t21.VERSION, t22.ID, t22.CREATE_TS, t22.CREATED_BY, t22.DELETE_TS, t22.DELETED_BY, t22.DESCRIPTION, t22.UPDATE_TS, t22.UPDATED_BY, t22.VERSION, t23.ID, t23.CODE, t23.CREATE_TS, t23.CREATED_BY, t23.DELETE_TS, t23.DELETED_BY, t23.DESCRIPTION, t23.UPDATE_TS, t23.UPDATED_BY, t23.VERSION, t24.ID, t24.CREATE_TS, t24.CREATED_BY, t24.DELETE_TS, t24.DELETED_BY, t24.DESCRIPTION, t24.UPDATE_TS, t24.UPDATED_BY, t24.VERSION, t25.ID, t25.CREATE_TS, t25.CREATED_BY, t25.DELETE_TS, t25.DELETED_BY, t25.DESCRIPTION, t25.UPDATE_TS, t25.UPDATED_BY, t25.VERSION, t26.ID, t26.CODE, t26.CREATE_TS, t26.CREATED_BY, t26.DELETE_TS, t26.DELETED_BY, t26.NAME, t26.UPDATE_TS, t26.UPDATED_BY, t26.VERSION, t26.GROUP_ID, t26.TYPE_ID, t27.ID, t27.CREATE_TS, t27.CREATED_BY, t27.DELETE_TS, t27.DELETED_BY, t27.FIAS_ID, t27.STREET_NAME, t27.UPDATE_TS, t27.UPDATED_BY, t27.VERSION, t27.LOCALITY_ID, t28.ID, t28.CREATE_TS, t28.CREATED_BY, t28.DELETE_TS, t28.DELETED_BY, t28.DESCRIPTION, t28.UPDATE_TS, t28.UPDATED_BY, t28.VERSION, t29.ID, t29.DTYPE, t29.CAPASCITY, t29.CREATE_TS, t29.CREATED_BY, t29.DELETE_TS, t29.DELETED_BY, t29.GPS_SH, t29.GPS_VD, t29.IS_UPLOADED_UP, t29.NOMINAL_VOLTAGE, t29.NUMBER_, t29.PC, t29.PC_FIDER, t29.UPDATE_TS, t29.UPDATED_BY, t29.VERSION, t29.IMPORT_STAGE_ID, t29.OBJ_ID, t29.STATUS_ID, t29.TYPE_ID, t30.ID, t30.DTYPE, t30.CREATE_TS, t30.CREATED_BY, t30.DELETE_TS, t30.DELETED_BY, t30.UPDATE_TS, t30.UPDATED_BY, t30.VERSION, t30.CONTRACT_ID, t30.EXECUTOR_ID, t30.LOCALITY_ID, t30.STATUS_ID, t30.HOME, t30.STRUCTURE, t30.TEHNICAL_CODE, t30.STREET_ID, t31.ID, t31.DTYPE, t31.CONTRACT_NAME, t31.CREATE_TS, t31.CREATED_BY, t31.DELETE_TS, t31.DELETED_BY, t31.UPDATE_TS, t31.UPDATED_BY, t31.VERSION, t31.CONTROLLER_ID, t31.OWNER_ID, t31.STATUS_ID, t32.ID, t32.CREATE_TS, t32.CREATED_BY, t32.DELETE_TS, t32.DELETED_BY, t32.FIAS_ID, t32.LOCALITY_NAME, t32.UPDATE_TS, t32.UPDATED_BY, t32.VERSION, t32.AREA_ID, t32.TYPE_ID, t33.ID, t33.AREA_NAME, t33.CREATE_TS, t33.CREATED_BY, t33.DELETE_TS, t33.DELETED_BY, t33.UPDATE_TS, t33.UPDATED_BY, t33.VERSION, t33.ZONE_ID, t34.ID, t34.CREATE_TS, t34.CREATED_BY, t34.DELETE_TS, t34.DELETED_BY, t34.NAME, t34.UPDATE_TS, t34.UPDATED_BY, t34.VERSION, t35.ID, t35.CREATE_TS, t35.CREATED_BY, t35.DELETE_TS, t35.DELETED_BY, t35.STAMP, t35.UPDATE_TS, t35.UPDATED_BY, t35.VERSION, t35.IKK_ID, t35.LOCKER_ID, t35.PARENT_ID, t35.TP_ID, t35.VOLTAGE_ID, t35.METER_ID, t36.ID, t36.ACC_CLASS, t36.CREATE_TS, t36.CREATED_BY, t36.DELETE_TS, t36.DELETED_BY, t36.IS_USED, t36.MAC, t36.NETWORK_ADRESS, t36.NEXT_VETIFICATION_YEAR, t36.NUMBER_, t36.PHASE, t36.TYPE_, t36.UPDATE_TS, t36.UPDATED_BY, t36.USE_DATE, t36.VERIFICATION_YEAR, t36.VERSION, t36.MANUFACTURER_ID FROM ENERSTROYMAIN_ACCOUNTING_POINT t1 LEFT OUTER JOIN ENERSTROYMAIN_GROUP_STAGE t0 ON (t0.ID = t1.IMPORT_STAGE_ID) LEFT OUTER JOIN ENERSTROYMAIN_METER t2 ON (t2.ID = t1.METER_ID) LEFT OUTER JOIN ENERSTROYMAIN_OBJECT t3 ON (t3.ID = t1.OBJ_ID) LEFT OUTER JOIN ENERSTROYMAIN_CONTRACT t4 ON (t4.ID = t3.CONTRACT_ID) LEFT OUTER JOIN SEC_GROUP t5 ON (t5.ID = t3.EXECUTOR_ID) LEFT OUTER JOIN ENERSTROYMAIN_LOCALITY t6 ON (t6.ID = t3.LOCALITY_ID) LEFT OUTER JOIN ENERSTROYMAIN_AREA t7 ON (t7.ID = t6.AREA_ID) LEFT OUTER JOIN ENERSTROYMAIN_ZONE t8 ON (t8.ID = t7.ZONE_ID) LEFT OUTER JOIN ENERSTROYMAIN_STATUS t9 ON (t9.ID = t3.STATUS_ID) LEFT OUTER JOIN ENERSTROYMAIN_STATUS_GROUP t10 ON (t10.ID = t9.GROUP_ID) LEFT OUTER JOIN ENERSTROYMAIN_GROUP_STAGE t11 ON (t11.ID = t10.STAGE_ID) LEFT OUTER JOIN ENERSTROYMAIN_TP_FEEDER t12 ON (t12.ID = t1.PPO_FEEDER_ID) LEFT OUTER JOIN ENERSTROYMAIN_TP_INPUT t13 ON (t13.ID = t12.INPUT_ID) LEFT OUTER JOIN ENERSTROYMAIN_TRANS_STATION t14 ON (t14.ID = t12.TP_ID) LEFT OUTER JOIN ENERSTROYMAIN_OBJECT t15 ON (t15.ID = t14.OBJ_ID) LEFT OUTER JOIN ENERSTROYMAIN_CONTRACT t16 ON (t16.ID = t15.CONTRACT_ID) LEFT OUTER JOIN ENERSTROYMAIN_LOCALITY t17 ON (t17.ID = t15.LOCALITY_ID) LEFT OUTER JOIN ENERSTROYMAIN_AREA t18 ON (t18.ID = t17.AREA_ID) LEFT OUTER JOIN ENERSTROYMAIN_ZONE t19 ON (t19.ID = t18.ZONE_ID) LEFT OUTER JOIN ENERSTROYMAIN_INPUT_TYPE t20 ON (t20.ID = t1.PPO_INPUT_TYPE_ID) LEFT OUTER JOIN ENERSTROYMAIN_MONTAGE_PLACE_STATUS t21 ON (t21.ID = t1.PPO_MONTAGE_PLACE_PU_ID) LEFT OUTER JOIN ENERSTROYMAIN_PHASE_ENUM t22 ON (t22.ID = t1.PPO_PHASE_ID) LEFT OUTER JOIN ENERSTROYMAIN_ADM_ACT_ENUM_SMR t23 ON (t23.ID = t1.SMR_ADM_ACT_ID) LEFT OUTER JOIN ENERSTROYMAIN_LINE_TYPE_SMR t24 ON (t24.ID = t1.SMR_LINE_TYPE_ID) LEFT OUTER JOIN ENERSTROYMAIN_MONTAGE_PLACE_ENUM t25 ON (t25.ID = t1.SMR_MONTAGE_PLACE_ID) LEFT OUTER JOIN ENERSTROYMAIN_STATUS t26 ON (t26.ID = t1.STATUS_ID) LEFT OUTER JOIN ENERSTROYMAIN_STREET t27 ON (t27.ID = t1.STREET_ID) LEFT OUTER JOIN ENERSTROYMAIN_SUBSCRIBER_TYPE t28 ON (t28.ID = t1.SUBSCRIBER_TYPE_ID) LEFT OUTER JOIN ENERSTROYMAIN_TRANS_STATION t29 ON (t29.ID = t1.TP_ID) LEFT OUTER JOIN ENERSTROYMAIN_OBJECT t30 ON (t30.ID = t29.OBJ_ID) LEFT OUTER JOIN ENERSTROYMAIN_CONTRACT t31 ON (t31.ID = t30.CONTRACT_ID) LEFT OUTER JOIN ENERSTROYMAIN_LOCALITY t32 ON (t32.ID = t30.LOCALITY_ID) LEFT OUTER JOIN ENERSTROYMAIN_AREA t33 ON (t33.ID = t32.AREA_ID) LEFT OUTER JOIN ENERSTROYMAIN_ZONE t34 ON (t34.ID = t33.ZONE_ID) LEFT OUTER JOIN ENERSTROYMAIN_TP_METER t35 ON (t35.ID = t1.TP_METER_ID) LEFT OUTER JOIN ENERSTROYMAIN_METER t36 ON (t36.ID = t35.METER_ID) WHERE ((t1.ID = ?) AND (t1.DELETE_TS IS NULL))
     bind => [cda7098b-4487-41f5-052a-2a50812ed0f3]
    2018-02-16 11:07:21.004 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - [39 ms] spent
    2018-02-16 11:07:21.005 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - SELECT ID, CREATE_TS, CREATED_BY, DELETE_TS, DELETED_BY, IS_VALID, UPDATE_TS, UPDATED_BY, VERSION, ACCOUNTING_POINT_ID, IMAGE_FILE_ID, STAGE_ID, TYPE_ID FROM ENERSTROYMAIN_ACCOUNTING_POINT_IMAGE WHERE ((ACCOUNTING_POINT_ID IN (?)) AND (DELETE_TS IS NULL))
     bind => [cda7098b-4487-41f5-052a-2a50812ed0f3]
    2018-02-16 11:07:21.010 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - [5 ms] spent
    2018-02-16 11:07:21.012 WARN [http-nio-8080-exec-17/ROOT-core/admin] com.company.enerstroymain.listener.AccountingPointEntityListener - Попытка присвоить нулевой этап добавления ТУ cda7098b-4487-41f5-052a-2a50812ed0f3 автоматически присвоен этап ТЗ
    2018-02-16 11:07:21.021 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - SELECT ID AS a1, CREATE_TS AS a2, CREATED_BY AS a3, DELETE_TS AS a4, DELETED_BY AS a5, STAGE AS a6, UPDATE_TS AS a7, UPDATED_BY AS a8, VERSION AS a9 FROM ENERSTROYMAIN_GROUP_STAGE WHERE ((STAGE = ?) AND (DELETE_TS IS NULL)) LIMIT ? OFFSET ?
     bind => [ТЗ, 1, 0]
    2018-02-16 11:07:21.021 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - [0 ms] spent
    2018-02-16 11:07:21.021 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - UPDATE ENERSTROYMAIN_ACCOUNTING_POINT SET IMPORT_STAGE_ID = ?, UPDATED_BY = ?, UPDATE_TS = ?, VERSION = ? WHERE ((ID = ?) AND (VERSION = ?))
     bind => [c350f53c-8b1c-bdb0-6114-f74513ba212d, admin, 2018-02-16 11:07:21.021, 2, cda7098b-4487-41f5-052a-2a50812ed0f3, 1]
    2018-02-16 11:07:21.021 DEBUG [http-nio-8080-exec-17/ROOT-core/admin] eclipselink.sql - [0 ms] spent
    2018-02-16 11:07:21.052 ERROR [http-nio-8080-exec-17/ROOT/admin] com.haulmont.cuba.web.log.AppLog - Exception in com.haulmont.cuba.web.toolkit.ui.CubaButton: 
    com.vaadin.server.ServerRpcManager$RpcInvocationException: Unable to invoke method click in com.vaadin.shared.ui.button.ButtonServerRpc
     at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:160) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:119) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.communication.ServerRpcHandler.handleInvocation(ServerRpcHandler.java:444) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:409) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:274) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:90) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:41) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1435) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:361) [vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:301) [cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:192) [cuba-web-6.7.9.jar:6.7.9]
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:742) [servlet-api.jar:na]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) [catalina.jar:8.5.21]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.21]
     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52) [tomcat-websocket.jar:8.5.21]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.21]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.21]
     at com.haulmont.cuba.web.sys.CubaHttpFilter.handleNotFiltered(CubaHttpFilter.java:116) [cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:103) [cuba-web-6.7.9.jar:6.7.9]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) [catalina.jar:8.5.21]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) [catalina.jar:8.5.21]
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199) [catalina.jar:8.5.21]
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [catalina.jar:8.5.21]
     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:478) [catalina.jar:8.5.21]
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140) [catalina.jar:8.5.21]
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81) [catalina.jar:8.5.21]
     at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650) [catalina.jar:8.5.21]
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87) [catalina.jar:8.5.21]
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342) [catalina.jar:8.5.21]
     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:799) [tomcat-coyote.jar:8.5.21]
     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-coyote.jar:8.5.21]
     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868) [tomcat-coyote.jar:8.5.21]
     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1459) [tomcat-coyote.jar:8.5.21]
     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-coyote.jar:8.5.21]
     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_161]
     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_161]
     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-util.jar:8.5.21]
     at java.lang.Thread.run(Thread.java:748) [na:1.8.0_161]
    Caused by: java.lang.reflect.InvocationTargetException: null
     at sun.reflect.GeneratedMethodAccessor308.invoke(Unknown Source) ~[na:na]
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
     at com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:158) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     ... 37 common frames omitted
    Caused by: com.vaadin.event.ListenerMethod$MethodException: Invocation of method buttonClick in com.haulmont.cuba.web.gui.components.WebButton$$Lambda$100/2101585776 failed.
     at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:530) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:200) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:163) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.server.AbstractClientConnector.fireEvent(AbstractClientConnector.java:1037) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.ui.Button.fireClick(Button.java:377) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.haulmont.cuba.web.toolkit.ui.CubaButton.fireClick(CubaButton.java:54) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.vaadin.ui.Button$1.click(Button.java:54) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     ... 41 common frames omitted
    Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
     at com.haulmont.cuba.gui.xml.DeclarativeAction.actionPerform(DeclarativeAction.java:94) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.components.WebButton.performAction(WebButton.java:44) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.components.WebButton.lambda$new$61446b05$1(WebButton.java:36) ~[cuba-web-6.7.9.jar:6.7.9]
     at sun.reflect.GeneratedMethodAccessor296.invoke(Unknown Source) ~[na:na]
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
     at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     ... 47 common frames omitted
    Caused by: java.lang.reflect.InvocationTargetException: null
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_161]
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_161]
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
     at com.haulmont.cuba.gui.xml.DeclarativeAction.actionPerform(DeclarativeAction.java:92) ~[cuba-gui-6.7.9.jar:6.7.9]
     ... 53 common frames omitted
    Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
     at com.haulmont.chile.core.model.utils.MethodsCache.invokeGetter(MethodsCache.java:74) ~[cuba-global-6.7.9.jar:6.7.9]
     at com.haulmont.chile.core.model.impl.AbstractInstance.getValue(AbstractInstance.java:102) ~[cuba-global-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.core.entity.BaseGenericIdEntity.getValue(BaseGenericIdEntity.java:140) ~[cuba-global-6.7.9.jar:6.7.9]
     at com.haulmont.chile.core.model.utils.InstanceUtils.getValueEx(InstanceUtils.java:139) ~[cuba-global-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.data.PropertyWrapper.getValue(PropertyWrapper.java:76) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.vaadin.ui.AbstractField.readValueFromProperty(AbstractField.java:1364) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.vaadin.ui.AbstractField.valueChange(AbstractField.java:1357) ~[vaadin-server-7.7.13.cuba.0.jar:7.7.13.cuba.0]
     at com.haulmont.cuba.web.gui.data.AbstractPropertyWrapper.fireValueChangeEvent(AbstractPropertyWrapper.java:58) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.data.PropertyWrapper.lambda$new$0(PropertyWrapper.java:54) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.data.impl.WeakItemChangeListener.itemChanged(WeakItemChangeListener.java:40) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.bali.events.EventRouter.fireEvent(EventRouter.java:45) ~[cuba-global-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.data.impl.AbstractDatasource.fireItemChanged(AbstractDatasource.java:283) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.data.impl.DatasourceImpl.committed(DatasourceImpl.java:251) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.data.impl.DsContextImpl.notifyAllDsCommited(DsContextImpl.java:234) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.data.impl.DsContextImpl.commit(DsContextImpl.java:170) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.components.EditorWindowDelegate.commit(EditorWindowDelegate.java:281) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.WebWindow$Editor.commit(WebWindow.java:1731) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.web.gui.WebWindow$Editor.commit(WebWindow.java:1723) ~[cuba-web-6.7.9.jar:6.7.9]
     at com.haulmont.cuba.gui.components.AbstractEditor.commit(AbstractEditor.java:86) ~[cuba-gui-6.7.9.jar:6.7.9]
     at com.company.enerstroymain.web.main.contacts.mkd.accountingpoint.MKDAccountingPointEdit.onSaveButtonClick(MKDAccountingPointEdit.java:62) ~[ROOT-web-0.1-SNAPSHOT.jar:na]
     ... 58 common frames omitted
    Caused by: java.lang.reflect.InvocationTargetException: null
     at sun.reflect.GeneratedMethodAccessor192.invoke(Unknown Source) ~[na:na]
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_161]
     at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_161]
     at com.haulmont.chile.core.model.utils.MethodsCache.invokeGetter(MethodsCache.java:72) ~[cuba-global-6.7.9.jar:6.7.9]
     ... 77 common frames omitted
    Caused by: org.eclipse.persistence.exceptions.ValidationException: 
    Exception Description: An attempt was made to traverse a relationship using indirection that had a null Session. This often occurs when an entity with an uninstantiated LAZY relationship is serialized and that relationship is traversed after serialization. To avoid this issue, instantiate the LAZY relationship prior to serialization.
     at org.eclipse.persistence.exceptions.ValidationException.instantiatingValueholderWithNullSession(ValidationException.java:1024) ~[eclipselink-2.6.2.cuba20.jar:2.6.2.cuba20]
     at org.eclipse.persistence.internal.indirection.UnitOfWorkValueHolder.instantiate(UnitOfWorkValueHolder.java:233) ~[eclipselink-2.6.2.cuba20.jar:2.6.2.cuba20]
     at org.eclipse.persistence.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:101) ~[eclipselink-2.6.2.cuba20.jar:2.6.2.cuba20]
     at com.company.enerstroymain.entity.contracts.mkd.MKDAccountingPoint._persistence_get_networkElement(MKDAccountingPoint.java) ~[ROOT-global-0.1-SNAPSHOT.jar:na]
     at com.company.enerstroymain.entity.contracts.mkd.MKDAccountingPoint.getNetworkElement(MKDAccountingPoint.java:141) ~[ROOT-global-0.1-SNAPSHOT.jar:na]
     ... 81 common frames omitted

Прошу прощения, если в итоге зафлудил. Но описание проблемы на форуме помогло вспомнить об очевидной причине ошибке:
BeforeInsert listener, определенный для суперкласса перезагружал сущность, что и вызывало ошибку при сохранении атрибута Child-класса.