android/guava/src/com/google/common/io/CharSource.java
@NullableDecl
  public String readFirstLine() throws IOException {
    Closer closer = Closer.create();
    try {
      BufferedReader reader = closer.register(openBufferedStream());
      return reader.readLine();
    } catch (Throwable e) {
      throw closer.rethrow(e);
    } finally {
      closer.close();
    }
  }
@NullableDecl
  public String readFirstLine() throws IOException {
    Closer closer = Closer.create();
    try {
      BufferedReader reader = closer.register(openBufferedStream());
      return reader.readLine();
    } catch (Throwable e) {
      throw closer.rethrow(e);
    } finally {
      closer.close();
    }
  }
Reads the first line of this source as a string. Returns {@code null} if this source is empty.

<p>Like {@link BufferedReader#readLine()}, this method considers a line to be a sequence of
text that is terminated by (but does not include) one of {@code \r\n}, {@code \r} or {@code
\n}. If the source's content does not end in a line termination sequence, it is treated as if
it does.

@throws IOException if an I/O error occurs while reading from this source