## 🏗️ Architecture & Design Patterns

### Core Design Principles
CoreLib follows a **utility-class pattern** where most functionality is exposed through static methods:

- **Assertion-based validation** - All methods validate inputs using `AssertionUtil.assertArgumentNotNull()` and `AssertionUtil.assertArgumentNotEmpty()`

//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// Package cmd This file implements helper functions to validate AWS
// Signature Version '4' authorization header.
//
// This package provides comprehensive helpers for following signature
// types.
// - Based on Authorization header.
// - Based on Query parameters.

* GCI: Update the command to get the image ([#24987](https://github.com/kubernetes/kubernetes/pull/24987), [@andyzheng0831](https://github.com/andyzheng0831))
* Validate deletion timestamp doesn't change on update ([#24839](https://github.com/kubernetes/kubernetes/pull/24839), [@liggitt](https://github.com/liggitt))

* Deleting federation-push.sh ([#27400](https://github.com/kubernetes/kubernetes/pull/27400), [@nikhiljindal](https://github.com/nikhiljindal))
* Validate-cluster finishes shortly after at most ALLOWED_NOTREADY_NODE… ([#26778](https://github.com/kubernetes/kubernetes/pull/26778), [@gmarek](https://github.com/gmarek))

        }
    }

    /**
     * Attempts to obtain login credentials using SPNEGO authentication.
     *
     * This method processes the HTTP request to extract and validate SPNEGO
     * authentication tokens. It handles the SPNEGO handshake process and
     * extracts the user principal from successful authentication.
     *

}

func (j xlMetaV2Version) getDataDir() string {
	if j.Valid() {
		switch j.Type {
		case LegacyType:
			return j.ObjectV1.DataDir
		case ObjectType:
			return uuid.UUID(j.ObjectV2.DataDir).String()
		}
	}
	return ""
}

// Valid xl meta xlMetaV2Version is valid
func (j xlMetaV2Version) Valid() bool {
	if !j.Type.valid() {
		return false
	}
	switch j.Type {
	case LegacyType:

	for _, rule := range lc.Rules {
		if rule.Transition.StorageClass != "" {
			if valid := globalTierConfigMgr.IsTierValid(rule.Transition.StorageClass); !valid {
				return errInvalidStorageClass
			}
		}
		if rule.NoncurrentVersionTransition.StorageClass != "" {
			if valid := globalTierConfigMgr.IsTierValid(rule.NoncurrentVersionTransition.StorageClass); !valid {
				return errInvalidStorageClass
			}
		}
	}
	return nil
}

		return entries, err
	}

	// Marker points to before the prefix, just ignore it.
	if o.Marker < o.Prefix {
		o.Marker = ""
	}

	// Marker is set validate pre-condition.
	if o.Marker != "" && o.Prefix != "" {
		// Marker not common with prefix is not implemented. Send an empty response
		if !HasPrefix(o.Marker, o.Prefix) {
			return entries, io.EOF
		}
	}

        headers_.add(name, value.toString())
      }

    /**
     * Adds a new header with the name and value. This may be used to add multiple headers with the
     * same name. Unlike [addHeader] this does not validate the name and
     * value.
     */
    public fun addHeaderLenient(
      name: String,
      value: Any,
    ): Builder =
      apply {
        addHeaderLenient(headers_, name, value.toString())

      Map<R, Map<C, V>> backingMap, Supplier<? extends Map<C, V>> factory) {
    checkArgument(backingMap.isEmpty());
    checkNotNull(factory);
    // TODO(jlevy): Wrap factory to validate that the supplied maps are empty?
    return new StandardTable<>(backingMap, factory);
  }

  /**
   * Returns a view of a table where each value is transformed by a function. All other properties