private int readStringIndex(ByteInput bs) throws IOException {
    int offsetIndex = Leb128.readUnsignedLeb128(bs);

    return offsetIndex - 1;
  }
Reads a string index. String indicies are offset by 1, and a 0 value in the stream (-1 as
returned by this method) means "null"

@return index into file's string ids table, -1 means null
@throws IOException
android/android_framework/dex-maker/src/main/java/com/android/dx/dex/file/DebugInfoDecoder.java