How to use

Sha1CollisionException

in

org.eclipse.jgit.util.sha1

private void finish() {
  int bufferLen = (int) (length & 63);
  if (bufferLen > 55) {
    // Last block is too small; pad, compress, pad another block.
    buffer[bufferLen++] = (byte) 0x80;
    Arrays.fill(buffer, bufferLen, 64, (byte) 0);
    compress(buffer, 0);
    Arrays.fill(buffer, 0, 56, (byte) 0);
  } else {
    // Last block can hold padding and length.
    buffer[bufferLen++] = (byte) 0x80;
    Arrays.fill(buffer, bufferLen, 56, (byte) 0);
  }
  // SHA-1 appends the length of the message in bits after the
  // padding block (above). Here length is in bytes. Multiply by
  // 8 by shifting by 3 as part of storing the 64 bit byte length
  // into the two words expected in the trailer.
  NB.encodeInt32(buffer, 56, (int) (length >>> (32 - 3)));
  NB.encodeInt32(buffer, 60, (int) (length << 3));
  compress(buffer, 0);
  if (foundCollision) {
    ObjectId id = h.toObjectId();
    LOG.warn("possible SHA-1 collision " + id.name()); //$NON-NLS-1$
    throw new Sha1CollisionException(id);
  }
}

private void finish() {
  int bufferLen = (int) (length & 63);
  if (bufferLen > 55) {
    // Last block is too small; pad, compress, pad another block.
    buffer[bufferLen++] = (byte) 0x80;
    Arrays.fill(buffer, bufferLen, 64, (byte) 0);
    compress(buffer, 0);
    Arrays.fill(buffer, 0, 56, (byte) 0);
  } else {
    // Last block can hold padding and length.
    buffer[bufferLen++] = (byte) 0x80;
    Arrays.fill(buffer, bufferLen, 56, (byte) 0);
  }
  // SHA-1 appends the length of the message in bits after the
  // padding block (above). Here length is in bytes. Multiply by
  // 8 by shifting by 3 as part of storing the 64 bit byte length
  // into the two words expected in the trailer.
  NB.encodeInt32(buffer, 56, (int) (length >>> (32 - 3)));
  NB.encodeInt32(buffer, 60, (int) (length << 3));
  compress(buffer, 0);
  if (foundCollision) {
    ObjectId id = h.toObjectId();
    LOG.warn("possible SHA-1 collision " + id.name()); //$NON-NLS-1$
    throw new Sha1CollisionException(id);
  }
}