Probably caused by the upgrade to ES 7.6.
Warning: it seems the problem is not detected by the maven-enforcer-plugin evertime, but rather one of two builds, something like that.
[2020-02-21 09:56:36] [autobuild] Dependency convergence error for org.apache.httpcomponents:httpcore:4.4.12 paths to dependency are: [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpclient:4.5.10 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore:4.4.12 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore:4.4.12 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpasyncclient:4.1.4 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore:4.4.10 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client-sniffer:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore:4.4.12 [2020-02-21 09:56:36] [autobuild] [WARNING] [2020-02-21 09:56:36] [autobuild] Dependency convergence error for org.apache.httpcomponents:httpclient:4.5.10 paths to dependency are: [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpclient:4.5.10 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpasyncclient:4.1.4 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpclient:4.5.6 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client-sniffer:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpclient:4.5.10 [2020-02-21 09:56:36] [autobuild] [WARNING] [2020-02-21 09:56:36] [autobuild] Dependency convergence error for commons-logging:commons-logging:1.2 paths to dependency are: [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpclient:4.5.10 [2020-02-21 09:56:36] [autobuild] +-commons-logging:commons-logging:1.2 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpasyncclient:4.1.4 [2020-02-21 09:56:36] [autobuild] +-commons-logging:commons-logging:1.2 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-commons-logging:commons-logging:1.1.3 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client-sniffer:7.6.0 [2020-02-21 09:56:36] [autobuild] +-commons-logging:commons-logging:1.1.3 [2020-02-21 09:56:36] [autobuild] [WARNING] [2020-02-21 09:56:36] [autobuild] Dependency convergence error for org.apache.httpcomponents:httpcore-nio:4.4.10 paths to dependency are: [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpasyncclient:4.1.4 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore-nio:4.4.10 [2020-02-21 09:56:36] [autobuild] and [2020-02-21 09:56:36] [autobuild] +-org.hibernate.search:hibernate-search-backend-elasticsearch:6.0.0-SNAPSHOT [2020-02-21 09:56:36] [autobuild] +-org.elasticsearch.client:elasticsearch-rest-client:7.6.0 [2020-02-21 09:56:36] [autobuild] +-org.apache.httpcomponents:httpcore-nio:4.4.12