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{