expected        map[string]string
	}{
		{
			metadata: map[string]string{
				"Authorization":        "AWS4-HMAC-SHA256 <cred_string>",
				"X-Amz-Content-Sha256": "",
				"Content-Encoding":     "",
			},
			expected: map[string]string{
				"Authorization":        "AWS4-HMAC-SHA256 <cred_string>",
				"X-Amz-Content-Sha256": "",
				"Content-Encoding":     "",
			},
		},
		{
			metadata: map[string]string{

			req: &http.Request{
				URL: &url.URL{
					Host:   "127.0.0.1:9000",
					Scheme: httpScheme,
					Path:   SlashSeparator,
				},
				Header: http.Header{
					"Authorization":        []string{"AWS4-HMAC-SHA256 <cred_string>"},
					"X-Amz-Content-Sha256": []string{streamingContentSHA256},
					"Content-Encoding":     []string{streamingContentEncoding},
				},
				Method: http.MethodPut,
				Body:   nopCloser,
			},