diff --git a/examples/bootstrap_examples.php b/examples/bootstrap_examples.php
index fc4793d..e266cb5 100644
--- a/examples/bootstrap_examples.php
+++ b/examples/bootstrap_examples.php
@@ -142,7 +142,7 @@ public function getOfficialLink() {
 	 * optionally helpers for the specific profile
 	 */
 	
-	public function setTimestamps(ResourceInterface $resource, \DateTimeInterface $created=null, \DateTimeInterface $updated=null) {
+	public function setTimestamps(ResourceInterface $resource, ?\DateTimeInterface $created=null, ?\DateTimeInterface $updated=null) {
 		if ($resource instanceof ResourceIdentifierObject) {
 			throw new Exception('cannot add attributes to identifier objects');
 		}
diff --git a/src/ErrorsDocument.php b/src/ErrorsDocument.php
index 025bc06..12f2ade 100644
--- a/src/ErrorsDocument.php
+++ b/src/ErrorsDocument.php
@@ -29,9 +29,9 @@ class ErrorsDocument extends Document {
 	];
 	
 	/**
-	 * @param ErrorObject $errorObject optional
+	 * @param ?ErrorObject $errorObject optional
 	 */
-	public function __construct(ErrorObject $errorObject=null) {
+	public function __construct(?ErrorObject $errorObject=null) {
 		parent::__construct();
 		
 		if ($errorObject !== null) {
diff --git a/src/helpers/RequestParser.php b/src/helpers/RequestParser.php
index 14a8373..a4abbc3 100644
--- a/src/helpers/RequestParser.php
+++ b/src/helpers/RequestParser.php
@@ -293,6 +293,18 @@ public function getAttribute($attributeName) {
 		return $this->document['data']['attributes'][$attributeName];
 	}
 	
+	/**
+	 * @param string $attributeName
+	 * @return mixed|null
+	 */
+	public function findAttribute($attributeName) {
+		if ($this->hasAttribute($attributeName) === false) {
+			return null;
+		}
+		
+		return $this->getAttribute($attributeName);
+	}
+	
 	/**
 	 * @param  string $relationshipName
 	 * @return boolean
diff --git a/tests/example_output/ExampleTimestampsProfile.php b/tests/example_output/ExampleTimestampsProfile.php
index 56b07f5..4426643 100644
--- a/tests/example_output/ExampleTimestampsProfile.php
+++ b/tests/example_output/ExampleTimestampsProfile.php
@@ -11,7 +11,7 @@ public function getOfficialLink() {
 		return 'https://jsonapi.org/recommendations/#authoring-profiles';
 	}
 	
-	public function setTimestamps(ResourceInterface $resource, \DateTimeInterface $created=null, \DateTimeInterface $updated=null) {
+	public function setTimestamps(ResourceInterface $resource, ?\DateTimeInterface $created=null, ?\DateTimeInterface $updated=null) {
 		if ($resource instanceof ResourceIdentifierObject) {
 			throw new Exception('cannot add attributes to identifier objects');
 		}