refactor: adds explicit nullable types

Author: JasonTheAdams

src/Models/Contracts/Model.php

@@ -56,7 +56,7 @@ public function getDirty() : array;
 	 *
 	 * @return mixed|array
 	 */
-	public function getOriginal( string $key = null );
+	public function getOriginal( ?string $key = null );
 
 	/**
 	 * Determines if the model has the given property.
@@ -79,7 +79,7 @@ public static function hasProperty( string $key ) : bool;
 	 *
 	 * @return bool
 	 */
-	public function isClean( string $attribute = null ) : bool;
+	public function isClean( ?string $attribute = null ) : bool;
 
 	/**
 	 * Determines if a given attribute is dirty.
@@ -90,7 +90,7 @@ public function isClean( string $attribute = null ) : bool;
 	 *
 	 * @return bool
 	 */
-	public function isDirty( string $attribute = null ) : bool;
+	public function isDirty( ?string $attribute = null ) : bool;
 
 	/**
 	 * Validates an attribute to a PHP type.

src/Models/Model.php

@@ -157,7 +157,7 @@ public function getDirty() : array {
 	 *
 	 * @return mixed|array
 	 */
-	public function getOriginal( string $key = null ) {
+	public function getOriginal( ?string $key = null ) {
 		return $key ? $this->original[ $key ] : $this->original;
 	}
 
@@ -322,7 +322,7 @@ public static function hasProperty( string $key ) : bool {
 	 *
 	 * @return bool
 	 */
-	public function isClean( string $attribute = null ) : bool {
+	public function isClean( ?string $attribute = null ) : bool {
 		return ! $this->isDirty( $attribute );
 	}
 
@@ -335,7 +335,7 @@ public function isClean( string $attribute = null ) : bool {
 	 *
 	 * @return bool
 	 */
-	public function isDirty( string $attribute = null ) : bool {
+	public function isDirty( ?string $attribute = null ) : bool {
 		if ( ! $attribute ) {
 			return (bool) $this->getDirty();
 		}

src/Models/ModelQueryBuilder.php

@@ -40,7 +40,7 @@ public function __construct( string $modelClass ) {
 	 *
 	 * @param null|string $column
 	 */
-	public function count( $column = null ) : int {
+	public function count( ?string $column = null ) : int {
 		$column = ( ! $column || $column === '*' ) ? '1' : trim( $column );
 
 		if ( '1' === $column ) {