New ocurrence of this kind of error, in this case I used getConversationsCallWithHttpInfo method of ConversationsApi from Java SDK v2-7.1.2:
Can not construct instance of java.util.Date from String value ("2017-07-10T09:36:09.719Z"): not a valid representation (error: For input string: "")
at [Source: {"id":"19695bba-5ed1-456c-bb78-0dbfc6274587","participants":[{"id":"384c3daf-e5d7-49cf-929e-2862d46d6588","name":"011111111111","address":"tel:111111111111","startTime":"2017-07-10T09:22:47.075Z","connectedTime":"2017-07-10T09:22:47.186Z","endTime":"2017-07-10T09:36:09.716Z","purpose":"customer","state":"disconnected","direction":"inbound","disconnectType":"endpoint","held":false,"wrapupRequired":false,"queue":{"id":"956f5b1f-31f5-4e93-93fa-c74f13b17710","selfUri":"/api/v2/routing/queues/956f5b1f-31f5-4e93-93fa-c74f13b17710"},"attributes":{"ScreenPopId":"7615a450-f8f3-11e6-9d3e-759112962d63","label":""CS Direct"","ScreenPopName":"SCRIPT-IN-SALES"},"script":{"id":"7615a450-f8f3-11e6-9d3e-759112962d63","selfUri":"/api/v2/scripts/7615a450-f8f3-11e6-9d3e-759112962d63"},"provider":"Edge","muted":false,"confined":false,"recording":false,"recordingState":"none","ani":"tel:111111111111","dnis":"tel:+33111111111"},{"id":"a088462c-acb9-437f-a708-3e56acbc964e","name":"France","address":"sip:b932bd96-8fb9-455b-bd5f-7b7271424cdc@127.0.0.1;language=fr-CA;user=ivr","startTime":"2017-07-10T09:22:47.102Z","connectedTime":"2017-07-10T09:22:47.156Z","endTime":"2017-07-10T09:22:48.619Z","purpose":"ivr","state":"disconnected","direction":"inbound","disconnectType":"transfer","held":false,"wrapupRequired":false,"attributes":{},"provider":"Edge","peer":"a860955d-ee3d-4a66-81cc-e8d693d029e6","muted":false,"confined":false,"recording":false,"recordingState":"none","ani":"tel:033111111111","dnis":"sip:b932bd96-8fb9-455b-bd5f-7b7271424cdc@127.0.0.1;language=fr-CA;user=ivr"},{"id":"e6496b58-4871-48fe-b7cc-4d8d42d034bd","name":"QUEUE-CS-INBOUND","address":"sip:956f5b1f-31f5-4e93-93fa-c74f13b17710@127.0.0.1;language=fr-CA;src=https://edge-proxy.eu-west-1.mypurecloud.ie/connector/v1/organizations/9bb3b84d-47ed-4038-a5c7-0c8700b788bb/defaults/ivr/f35fbfe0-24fa-4abc-91a5-8c81bd5ec1cc/defaultentrypoint.vxml;user=acd","startTime":"2017-07-10T09:22:48.564Z","connectedTime":"2017-07-10T09:22:48.612Z","endTime":"2017-07-10T09:25:43.652Z","purpose":"acd","state":"disconnected","direction":"inbound","disconnectType":"transfer","held":false,"wrapupRequired":false,"queue":{"id":"956f5b1f-31f5-4e93-93fa-c74f13b17710","selfUri":"/api/v2/routing/queues/956f5b1f-31f5-4e93-93fa-c74f13b17710"},"attributes":{"ivr.Priority":"8","ivr.Skills":"bcf7b0f1-e595-4660-9afc-e64f74393b41"},"provider":"Edge","peer":"a860955d-ee3d-4a66-81cc-e8d693d029e6","muted":false,"confined":false,"recording":false,"recordingState":"none","ani":"tel:033620035107","dnis":"sip:956f5b1f-31f5-4e93-93fa-c74f13b17710@127.0.0.1;language=fr-CA;src=https://edge-proxy.eu-west-1.mypurecloud.ie/connector/v1/organizations/9bb3b84d-47ed-4038-a5c7-0c8700b788bb/defaults/ivr/f35fbfe0-24fa-4abc-91a5-8c81bd5ec1cc/defaultentrypoint.vxml;user=acd"},{"id":"9ef27660-acb6-4c17-8f16-05106ee4880d","address":"sip:C5YPPZ1.internal.lan_1@10.98.0.250","startTime":"2017-07-10T09:25:43.538Z","connectedTime":"2017-07-10T09:25:43.682Z","endTime":"2017-07-10T09:36:09.719Z","purpose":"agent","state":"disconnected","direction":"inbound","disconnectType":"peer","held":false,"wrapupRequired":true,"wrapupPrompt":"timeout","user":{"id":"6f35854b-9143-49cf-8b5d-7961d56934bd","selfUri":"/api/v2/users/6f35854b-9143-49cf-8b5d-7961d56934bd"},"queue":{"id":"956f5b1f-31f5-4e93-93fa-c74f13b17710","selfUri":"/api/v2/routing/queues/956f5b1f-31f5-4e93-93fa-c74f13b17710"},"attributes":{"InteractionID":"{{Scripter.Interaction ID}}","AgentName":" {{Scripter.Agent Name}}"},"wrapupTimeoutMs":15000,"provider":"Edge","wrapup":{"code":"ININ-WRAP-UP-TIMEOUT","tags":[],"durationSeconds":15,"endTime":"2017-07-10T09:36:24.972Z"},"peer":"a860955d-ee3d-4a66-81cc-e8d693d029e6","muted":false,"confined":false,"recording":false,"recordingState":"none","ani":"sip:033111111111@10.98.0.251;user=phone","dnis":"sip:C5YPPZ1.internal.lan_1@10.98.0.250"}],"otherMediaUris":[],"recordingState":"none","selfUri":"/api/v2/conversations/calls/19695bba-5ed1-456c-bb78-0dbfc6274587"}; line: 1, column: 2996] (through reference chain: com.mypurecloud.sdk.v2.model.CallConversation["participants"]->java.util.ArrayList[3]->com.mypurecloud.sdk.v2.model.CallMediaParticipant["endTime"])
If you can see, the error is for endTime attribute in CallMediaParticipant, it's curious because the previous error was also in a segmentEnd attribute of segment... Could it be that Purecloud doesn't set correctly datetime fields?