UnsupportedClassVersionError: SonarQubeMojo : Unsupported major.minor version 52.0

also this is unrelated to the plugin, sonarqube has updated the default version of the sonar-maven-plugin to version 3.2. This requires java 8.

To solve the issue you need to update the JAVA_HOME to version 1.8 or use older version of sonar-maven-plugin, example:

export JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk1.8.0_45.jdk/Contents/Home/"

or

<plugin>  <groupId>org.codehaus.mojo</groupId>  <artifactId>sonar-maven-plugin</artifactId>  <version>2.6</version></plugin>