robolectric/src/main/java/org/robolectric/internal/dependency/LocalDependencyResolver.java
private static File validateFile(File file) throws IllegalArgumentException {
    if (!file.isFile()) {
      throw new IllegalArgumentException("Path is not a file: " + file);
    }
    if (!file.canRead()) {
      throw new IllegalArgumentException("Unable to read file: " + file);
    }
    return file;
  }
private static File validateFile(File file) throws IllegalArgumentException {
    if (!file.isFile()) {
      throw new IllegalArgumentException("Path is not a file: " + file);
    }
    if (!file.canRead()) {
      throw new IllegalArgumentException("Unable to read file: " + file);
    }
    return file;
  }
Validates {@code file} is an existing file that is readable.

@param file the File to test
@return the provided file, if all validation passes
@throws IllegalArgumentException if validation fails