code: public static File getSpringBootUberJARLocation(MavenProject project, Log log) {
          String classifier = getSpringBootMavenPluginClassifier(project, log);
  
          if (classifier == null) {
              classifier = "";
          }
          if (!classifier.isEmpty() && !classifier.startsWith("-")) {
              classifier = "-" + classifier;
          }
  
          return new File(project.getBuild().getDirectory(), project.getBuild().getFinalName() + classifier
                  + "." + project.getArtifact().getArtifactHandler().getExtension());
  
      }
docs: Get the Spring Boot Uber JAR in its expected location, taking into account the
  spring-boot-maven-plugin classifier configuration as well.  No validation is done,
  that is, there is no guarantee the JAR file actually exists at the returned location.
  
  @param outputDirectory
  @param project
  @param log
  @return the File representing the JAR location, whether a file exists there or not.