Warning message at ```mvn clean install -DskipTests```

build.log

[INFO] Scanning for projects...
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-api:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-common:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-runtime-library:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-runtime-internals:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-mapreduce:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-mapreduce-examples:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-tests:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-dag:jar:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-dist:pom:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez-docs:pom:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ org.apache.tez:tez:0.5.0-incubating-SNAPSHOT, /Users/ozawa/workspace/tez/pom.xml, line 496, column 17
[WARNING] 
[WARNING] Some problems were encountered while building the effective model for org.apache.tez:tez:pom:0.5.0-incubating-SNAPSHOT
[WARNING] 'build.pluginManagement.plugins.plugin.(groupId:artifactId)' must be unique but found duplicate declaration of plugin org.codehaus.mojo:findbugs-maven-plugin @ line 496, column 17
[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]