code: void installAdditional(final File installedFile, final String fileExt, final String payload, final boolean chop)
              throws MojoExecutionException {
          File additionalFile = null;
          if (chop) {
              String path = installedFile.getAbsolutePath();
              additionalFile = new File(path.substring(0, path.lastIndexOf('.')) + fileExt);
          } else {
              if (fileExt.indexOf('.') > 0) {
                  additionalFile = new File(installedFile.getParentFile(), fileExt);
              } else {
                  additionalFile = new File(installedFile.getAbsolutePath() + fileExt);
              }
          }
          getLog().debug("Installing additional file to " + additionalFile);
          try {
              additionalFile.getParentFile().mkdirs();
              FileUtils.fileWrite(additionalFile.getAbsolutePath(), "UTF-8", payload);
          } catch (IOException e) {
              throw new MojoExecutionException("Failed to install additional file to " + additionalFile, e);
          }
      }
docs: Installs additional files into the same repo directory as the artifact.
  
  @param installedFile The artifact to which this additional file is related
  @param fileExt The full file name or extension (begins with .) of the additional file
  @param payload The String to write to the additional file
  @param chop True of it replaces the artifact extension, false to attach the extension
  @throws MojoExecutionException In case of installation error