Java or Java-like files with alternate extensions are skipped.

Main.java has a very simple path extension check.

```java
for (String fileName : parameters.files()) {
if (!fileName.endsWith(".java")) {
errWriter.println("Skipping non-Java file: " + fileName);
continue;
}
```

Is there any reason alternate file extensions can't be formatting/supported? You can somewhat get around this by using standard input formatting and --assume-filename, so you can get around this with some additional tooling, but the restriction on the extension seems to be more out of an abundance of caution for throwing mixed source directories and folder structures.

My original intention was to see how well GJF does on AIDL files which kicked of my investigation into my options.

Start in Main.java at the path-extension check shown in the issue, and review how standard input with --assume-filename currently handles alternate names. Determine the supported behavior for Java-like extensions, then add coverage for the chosen cases and confirm that ordinary non-Java files are still skipped.

Escrita pelo modelo de indexação a partir do texto da issue.