stringToSign := getStringToSignV2(method, encodedResource, encodedQuery, headers, "")
	signature := calculateSignatureV2(stringToSign, cred.SecretKey)
	return signature
}

// compareSignatureV2 returns true if and only if both signatures
// are equal. The signatures are expected to be base64 encoded strings
// according to the AWS S3 signature V2 spec.
func compareSignatureV2(sig1, sig2 string) bool {

// HTTP requests made by all clients
type HTTPStats struct {
	s3RequestsInQueue       int32 // ref: https://golang.org/pkg/sync/atomic/#pkg-note-BUG
	_                       int32 // For 64 bits alignment
	s3RequestsIncoming      uint64
	rejectedRequestsAuth    uint64
	rejectedRequestsTime    uint64
	rejectedRequestsHeader  uint64
	rejectedRequestsInvalid uint64
	currentS3Requests       HTTPAPIStats

Until we can provide the same guarantees for core plugins, we need to be more conservative for existing classes and not follow best practices. This means conventions need to be set in both a plugin and the constructor. This keeps existing builds working, but it may complicate the implementation.

This is preferred for entirely new things:

```groovy
public interface NewThing {

Interceptors can be chained. Suppose you have both a compressing interceptor and a checksumming interceptor: you'll need to decide whether data is compressed and then checksummed, or checksummed and then compressed. OkHttp uses lists to track interceptors, and interceptors are called in order.

- circular dependency
- artifact missing
- artifact retrieval exception
- md5 checksum doesn't match for local artifact, need to redownload this
- POM doesn't exist for a goal that requires one
- parent POM missing (in both the repository + relative path)
- component not found

Plugins:
- plugin metadata missing
- plugin metadata retrieval problem
- plugin artifact missing
- plugin artifact retrieval problem

			ModTime:  time.Unix(0, 0),
			Typeflag: '2',
			PAXRecords: map[string]string{
				"linkpath": "PAX4/PAX4/long-linkpath-name",
			},
			Format: FormatPAX,
		}},
	}, {
		// Both BSD and GNU tar truncate long names at first NUL even
		// if there is data following that NUL character.
		// This is reasonable as GNU long names are C-strings.
		file: "testdata/gnu-long-nul.tar",
		headers: []*Header{{

type Fault int

const (
	None Fault = iota
	MissingContentLength
	TooBigObject
	TooBigDecodedLength
	BadSignature
	BadMD5
	MissingUploadID
)

// Wrapper for calling HeadObject API handler tests for both Erasure multiple disks and FS single drive setup.
func TestAPIHeadObjectHandler(t *testing.T) {
	ExecObjectLayerAPITest(ExecObjectLayerAPITestArgs{t: t, objAPITest: testAPIHeadObjectHandler, endpoints: []string{"HeadObject"}})
}

	if _, err := io.ReadFull(r, buf[off:12]); err != nil {
		return err
	}
	b := readBuf(buf[:12])
	if b.uint32() != f.CRC32 {
		return ErrChecksum
	}

	// The two sizes that follow here can be either 32 bits or 64 bits
	// but the spec is not very clear on this and different
	// interpretations has been made causing incompatibilities. We
	// already have the sizes from the central directory so we can
	// just ignore these.

         * prefer to propagate an IllegalArgumentException to the caller. However, we don't want to
         * simply rethrow an exception (e.getCause()) that may in rare cases have come from another
         * thread. To accomplish both goals, we wrap that IllegalArgumentException in a new
         * instance.
         */
        throw new IllegalArgumentException(e.getCause().getMessage(), e.getCause());
      }
      /*

    // 3) array has no space available
    //
    // In case 2 we shift the existing chars to the left, and in case 3 we create a bigger
    // array, then they both become case 1.

    if (availableCapacity(charBuffer) == 0) {
      if (charBuffer.position() > 0) {
        // (2) There is room in the buffer. Move existing bytes to the beginning.