Maven build produces warnings due to duplicated plugins

$ mvn clean
[INFO] Scanning for projects...
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.zeppelin:flink-scala-parent:pom:0.11.0-SNAPSHOT
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.flink:flink-connector-hive_${flink.scala.binary.version}:jar -> duplicate declaration of version ${flink.version} @ line 304, column 17
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.flink:flink-connector-hive_${flink.scala.binary.version}:jar:tests -> duplicate declaration of version ${flink.version} @ line 320, column 17
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:build-helper-maven-plugin @ line 852, column 15
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.zeppelin:flink-scala-2.11:jar:0.11.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:build-helper-maven-plugin @ line 51, column 15
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-resources-plugin @ line 71, column 15
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.flink:flink-connector-hive_${flink.scala.binary.version}:jar -> duplicate declaration of version ${flink.version} @ org.apache.zeppelin:flink-scala-parent:0.11.0-SNAPSHOT, /home/martin/git/apache/zeppelin/flink/flink-scala-parent/pom.xml, line 304, column 17
[WARNING] 'dependencies.dependency.(groupId:artifactId:type:classifier)' must be unique: org.apache.flink:flink-connector-hive_${flink.scala.binary.version}:jar:tests -> duplicate declaration of version ${flink.version} @ org.apache.zeppelin:flink-scala-parent:0.11.0-SNAPSHOT, /home/martin/git/apache/zeppelin/flink/flink-scala-parent/pom.xml, line 320, column 17
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:build-helper-maven-plugin @ org.apache.zeppelin:flink-scala-parent:0.11.0-SNAPSHOT, /home/martin/git/apache/zeppelin/flink/flink-scala-parent/pom.xml, line 852, column 15
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.zeppelin:flink-scala-2.12:jar:0.11.0-SNAPSHOT
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:build-helper-maven-plugin @ line 51, column 15
[WARNING] 'build.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.apache.maven.plugins:maven-resources-plugin @ line 71, column 15
[WARNING] 
[WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
[WARNING] 
[WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
[WARNING] 
[INFO] ------------------------------------------------------------------------