if you are curious and want to know how maven produce release version and next version you can try to debug its behavior by using following code:

import org.apache.maven.shared.release.versions.DefaultVersionInfo;
import org.apache.maven.shared.release.versions.VersionParseException;

public static void main(String []args){
    try {
        String version = "1.2.3-SNAPSHOT";
        DefaultVersionInfo v = new DefaultVersionInfo(version);
        System.out.println("version         : " + version);
        System.out.println("release version : " + v.getReleaseVersionString());
        System.out.println("next verison    : " + v.getNextVersion());
    } catch (VersionParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
}

don’t forget to add maven-release-manager in classpath or in your project pom as dependency