it-tests failing due to unexpected AclJsonEnricher output

It tests fail because of some error logged by the AclJsonEnricher.

when writing the json object, last token is not null and is stuck to last position because the temporary json output only has a start object without and end object. This results in failing further check (to make sure all tokens were processed) and logging this error

failing job: https://qa.nuxeo.org/jenkins/view/P1Fail/job/Deploy/job/IT-nuxeo-master-tests-cap-tomcat/267/

Looking into webdriver's server.log:

https://qa.nuxeo.org/jenkins/view/P1Fail/job/Deploy/job/IT-nuxeo-master-tests-cap-tomcat/267/artifact/tomcat-webdriver/log/server.log

 we find:

2020-02-28T05:23:19,628 ERROR [http-nio-0.0.0.0-8080-exec-1] [org.nuxeo.ecm.core.io.marshallers.json.enrichers.AbstractJsonEnricher] Enricher acls returned invalid output [TokenBuffer: START_OBJECT, FIELD_NAME(acls), START_ARRAY, START_OBJECT, FIELD_NAME(name), VALUE_STRING, FIELD_NAME(aces), START_ARRAY, START_OBJECT, FIELD_NAME(id), VALUE_STRING, FIELD_NAME(username), START_OBJECT, FIELD_NAME(entity-type), VALUE_STRING, FIELD_NAME(id), VALUE_STRING, FIELD_NAME(properties), START_OBJECT, FIELD_NAME(firstName), VALUE_NULL, FIELD_NAME(lastName), VALUE_NULL, FIELD_NAME(tenantId), VALUE_NULL, FIELD_NAME(groups), START_ARRAY, END_ARRAY, FIELD_NAME(company), VALUE_NULL, FIELD_NAME(email), VALUE_STRING, FIELD_NAME(username), VALUE_STRING, END_OBJECT, FIELD_NAME(extendedGroups), START_ARRAY, END_ARRAY, FIELD_NAME(isAdministrator), VALUE_FALSE, FIELD_NAME(isAnonymous), VALUE_FALSE, END_OBJECT, FIELD_NAME(externalUser), VALUE_FALSE, FIELD_NAME(permission), VALUE_STRING, FIELD_NAME(granted), VALUE_TRUE, FIELD_NAME(creator), START_OBJECT, FIELD_NAME(entity-type), VALUE_STRING, FIELD_NAME(id), VALUE_STRING, FIELD_NAME(properties), START_OBJECT, FIELD_NAME(firstName), VALUE_STRING, FIELD_NAME(lastName), VALUE_STRING, FIELD_NAME(tenantId), VALUE_NULL, FIELD_NAME(groups), START_ARRAY, END_ARRAY, FIELD_NAME(company), VALUE_STRING, FIELD_NAME(email), VALUE_STRING, FIELD_NAME(username), VALUE_STRING, END_OBJECT, FIELD_NAME(extendedGroups), START_ARRAY, END_ARRAY, FIELD_NAME(isAdministrator), VALUE_FALSE, FIELD_NAME(isAnonymous), VALUE_FALSE, END_OBJECT, FIELD_NAME(begin), VALUE_NULL, FIELD_NAME(end), VALUE_NULL, FIELD_NAME(status), VALUE_STRING, FIELD_NAME(comment), VALUE_STRING, FIELD_NAME(notify), VALUE_TRUE, END_OBJECT, END_ARRAY, END_OBJECT, START_OBJECT, FIELD_NAME(name), VALUE_STRING, FIELD_NAME(aces), START_ARRAY, START_OBJECT ... (truncated 172 entries)]