guava/src/com/google/common/hash/HashingInputStream.java
@Override
  @CanIgnoreReturnValue
  public int read() throws IOException {
    int b = in.read();
    if (b != -1) {
      hasher.putByte((byte) b);
    }
    return b;
  }
@Override
  @CanIgnoreReturnValue
  public int read() throws IOException {
    int b = in.read();
    if (b != -1) {
      hasher.putByte((byte) b);
    }
    return b;
  }
Reads the next byte of data from the underlying input stream and updates the hasher with the
byte read.