code: @VisibleForTesting
  	static Optional<String> findEntryClass(File jarFile) throws IOException {
  		return findFirstManifestAttribute(
  			jarFile,
  			PackagedProgram.MANIFEST_ATTRIBUTE_ASSEMBLER_CLASS,
  			PackagedProgram.MANIFEST_ATTRIBUTE_MAIN_CLASS);
  	}
docs: Returns the entry class as specified in the manifest of the provided JAR file.
  
  <p>The following manifest attributes are checked in order to find the entry class:
  <ol>
  <li>{@link PackagedProgram#MANIFEST_ATTRIBUTE_ASSEMBLER_CLASS}</li>
  <li>{@link PackagedProgram#MANIFEST_ATTRIBUTE_MAIN_CLASS}</li>
  </ol>
  
  @param jarFile JAR file to parse
  @return Optional holding entry class
  @throws IOException If there is an error accessing the JAR