diff --git a/d97637caf43966a4293e98526aa8804762fe43a2 b/0bfa773fc80a214396f5c4441d3fc97ea1215cda
index d97637c..0bfa773 100644
--- a/d97637caf43966a4293e98526aa8804762fe43a2
+++ b/0bfa773fc80a214396f5c4441d3fc97ea1215cda
@@ -5,6 +5,7 @@
 	reportMixedIssues="false"
   findUnusedPsalmSuppress="true"
   findUnusedBaselineEntry="true"
+  findUnusedCode="false"
 	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	xmlns="https://getpsalm.org/schema/config"
 	xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"

diff --git a/ceda524845255f96824216ccf0e678a49e59f53d b/69958a66e10c26fd6ae1912e172cf3762a78fb6b
index ceda524..69958a6 100644
--- a/ceda524845255f96824216ccf0e678a49e59f53d
+++ b/69958a66e10c26fd6ae1912e172cf3762a78fb6b
@@ -9,24 +9,26 @@

 namespace holonet\common\collection;

-use Countable;
 use ArrayAccess;
 use ArrayIterator;
+use Countable;
+use Iterator;
 use IteratorAggregate;
-use holonet\common\ComparableInterface;
+use OutOfBoundsException;

 /**
  * The ChangeAwareCollection is used as a wrapper around an array
  * it keeps track internally on how it's data changed.
+ * @psalm-suppress MissingTemplateParam
  */
-class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countable, IteratorAggregate {
+class ChangeAwareCollection implements Countable, ArrayAccess, IteratorAggregate {
 	/**
 	 * Array with $all keys of newly added entries.
 	 */
 	protected array $added = array();

 	/**
-	 * @var array<int|string, mixed> $all An array containing all entries
+	 * @var array<string, mixed> $all An array containing all entries
 	 */
 	protected array $all = array();

@@ -49,35 +51,28 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 	 * @param mixed $entry Either the key or the value that changes
 	 * @return mixed reference to the value or null if it doesn't exist
 	 */
-	public function &change($entry): mixed {
+	public function &change(mixed $entry): mixed {
 		$key = $this->findKeyForKeyOrEntry($entry);
 		if ($key !== null) {
 			$this->changed[] = $key;

 			return $this->all[$key];
 		}
+
+		throw new OutOfBoundsException("Entry not found");
 	}

 	/**
 	 * @param mixed $val The data entry to be saved
-	 * @param string|null $key The key to save the entry under
+	 * @param string $key The key to save the entry under
 	 * @param bool $new Flag marking this entry as not new (not to be saved into $this->added)
 	 */
-	public function add($val, ?string $key = null, bool $new = true): void {
+	public function add(mixed $val, string $key, bool $new = true): void {
 		if (is_object($val) && is_subclass_of($val, ChangeAwareInterface::class)) {
 			$val->belongsTo($this);
-			//not every change aware object can know about a unique key
-			if (method_exists($val, 'uniqKey') && $key === null) {
-				$key = $val->uniqKey();
-			}
 		}

-		if ($key === null) {
-			$this->all[] = $val;
-			$key = array_search($val, $this->all, true);
-		} else {
-			$this->all[$key] = $val;
-		}
+		$this->all[$key] = $val;

 		//if the override flag wasn't given, mark the entry as newly added
 		if ($new) {
@@ -90,8 +85,8 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 	 * @param bool $new Flag marking these entries as not new (not to be saved into $this->added)
 	 */
 	public function addAll(array $values, bool $new = true): void {
-		foreach ($values as $val) {
-			$this->add($val, null, $new);
+		foreach ($values as $key => $val) {
+			$this->add($val, $key, $new);
 		}
 	}

@@ -109,19 +104,6 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 		return !empty($this->added) || !empty($this->removed) || !empty($this->changed);
 	}

-	/**
-	 * compare this attribute set to another attribute set.
-	 * @param ComparableInterface $other The other object to compare this one to
-	 * @return bool if this object should be considered the same attribute set as the other one
-	 */
-	public function compareTo(ComparableInterface $other): bool {
-		if (!$other instanceof self) {
-			return false;
-		}
-
-		return $this->compareToCollection($other);
-	}
-
 	/**
 	 * Only counts the "current" entries
 	 * {@inheritDoc}
@@ -143,6 +125,8 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 		if (isset($this->all[$key]) && !in_array($key, $this->removed)) {
 			return $this->all[$key];
 		}
+
+		return null;
 	}

 	/**
@@ -188,60 +172,8 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 		return $this->all;
 	}

-	/**
-	 * {@inheritDoc}
-	 */
-	public function getIterator(): ArrayIterator {
-		return new ArrayIterator($this->getAll());
-	}
-
-	public function has($value): bool {
-		//if the given value is comparable, we can use that to find it
-		if (is_object($value) && $value instanceof ComparableInterface) {
-			foreach ($this->getAll('current') as $entry) {
-				if (is_object($entry) && $entry instanceof ComparableInterface && $entry->compareTo($value)) {
-					return true;
-				}
-			}
-		} else {
-			return in_array($value, $this->getAll('current'), true);
-		}
-
-		return false;
-	}
-
-	/**
-	 * Does not return true for "removed" entries.
-	 * {@inheritDoc}
-	 */
-	public function offsetExists($offset): bool {
-		return isset($this->all[$offset]) && !in_array($offset, $this->removed);
-	}
-
-	/**
-	 * Does only return values that aren't "removed".
-	 * {@inheritDoc}
-	 * @see self::get()
-	 */
-	public function offsetGet($offset) {
-		return $this->get($offset);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * @see self::set()
-	 */
-	public function offsetSet($offset, $value): void {
-		$this->set($offset, $value);
-	}
-
-	/**
-	 * Does only add the entry to "removed".
-	 * {@inheritDoc}
-	 * @see self::remove()
-	 */
-	public function offsetUnset($offset): void {
-		$this->remove($offset);
+	public function has(mixed $value): bool {
+		return $this->findKeyForKeyOrEntry($value) !== null;
 	}

 	/**
@@ -249,7 +181,7 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 	 * @param mixed $entry Either the key or the value that changes
 	 * @return bool true or false on success or not
 	 */
-	public function remove($entry): bool {
+	public function remove(mixed $entry): bool {
 		$key = $this->findKeyForKeyOrEntry($entry);
 		if ($key !== null) {
 			$this->removed[] = $key;
@@ -273,15 +205,15 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 	/**
 	 * setter function to set a value by its key
 	 * either calls the add function or set the value.
-	 * @param string|null $key The key for the value
+	 * @param string $key The key for the value
 	 * @param mixed $value The value that is to be set
 	 */
-	public function set(?string $key, $value): void {
-		if ($key === null || !array_key_exists($key, $this->all)) {
+	public function set(string $key, mixed $value): void {
+		if (!array_key_exists($key, $this->all)) {
 			$this->add($value, $key);
 		} else {
 			if ($this->all[$key] !== $value) {
-				$this->change($key);
+				$this->changed[] = $key;
 			}

 			if (is_object($value) && is_subclass_of($value, ChangeAwareInterface::class)) {
@@ -292,16 +224,6 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 		}
 	}

-	/**
-	 * compare this attribute set to another attribute set.
-	 * @param ChangeAwareCollection $other The other object to compare this one to
-	 * @return bool if this object should be considered the same attribute set as the other one
-	 */
-	private function compareToCollection(self $other): bool {
-		return $this->all === $other->all && $this->changed === $other->changed
-			&& $this->added === $other->added && $this->removed === $other->removed;
-	}
-
 	/**
 	 * helper function to figure out what an argument is
 	 * first assumes the argument is a key
@@ -310,19 +232,46 @@ class ChangeAwareCollection implements ArrayAccess, ComparableInterface, Countab
 	 * @param mixed $entry Either the key or the value
 	 * @return mixed|null the key of the value/the key if it's a key
 	 */
-	private function findKeyForKeyOrEntry($entry): mixed {
+	private function findKeyForKeyOrEntry(mixed $entry): ?string {
 		//check if $entry is an array key (allow null, so no isset)
-		if ((is_string($entry) || is_int($entry)) && array_key_exists($entry, $this->all)) {
+		if (is_string($entry) && array_key_exists($entry, $this->all)) {
 			return $entry;
 		}
-		if (is_object($entry) && $entry instanceof ComparableInterface) {
-			foreach ($this->all as $key => $value) {
-				if ($value instanceof ComparableInterface && $entry->compareTo($value)) {
-					return $key;
-				}
-			}
-		} elseif (($key = array_search($entry, $this->all)) !== false) {
+
+		if (($key = array_search($entry, $this->all, true)) !== false) {
 			return $key;
 		}
+
+		return null;
+	}
+
+	public function offsetExists(mixed $offset): bool {
+		// specifically use isset() in order to return false on null values
+		return isset($this->all[$offset]) && !in_array($offset, $this->removed);
+	}
+
+	/**
+	 * @see self::get()
+	 */
+	public function offsetGet(mixed $offset): mixed {
+		return $this->get($offset);
+	}
+
+	/**
+	 * @see self::set()
+	 */
+	public function offsetSet(mixed $offset, mixed $value): void {
+		$this->set($offset, $value);
+	}
+
+	/**
+	 * @see self::remove()
+	 */
+	public function offsetUnset(mixed $offset): void {
+		$this->remove($offset);
+	}
+
+	public function getIterator(): Iterator {
+		return new ArrayIterator($this->getAll());
 	}
 }

diff --git a/d10b0620b948e97a9d30827c4f190cfe1611d0f6 b/d6a2eac05bc14dd84411460028e13cf6e055c3e9
index d10b062..d6a2eac 100644
--- a/d10b0620b948e97a9d30827c4f190cfe1611d0f6
+++ b/d6a2eac05bc14dd84411460028e13cf6e055c3e9
@@ -13,7 +13,7 @@ trait ChangeAwareTrait {
 	/**
 	 * holds a reference to the ChangeAwareCollection that is keeping track of this object.
 	 */
-	private ChangeAwareCollection $partOfCollection;
+	private ?ChangeAwareCollection $partOfCollection = null;

 	/**
 	 * @param ChangeAwareCollection $coll A reference to the collection this object is part of

diff --git a/a032ecc3cd200babc8e821b4c22b6afbc67a0651 b/1143f81053f5f8ef420d7160d252fae32606b2b4
index a032ecc..1143f81 100644
--- a/a032ecc3cd200babc8e821b4c22b6afbc67a0651
+++ b/1143f81053f5f8ef420d7160d252fae32606b2b4
@@ -10,15 +10,18 @@
 namespace holonet\common\collection;

 use Countable;
-use ArrayAccess;
 use ArrayIterator;
 use IteratorAggregate;

 /**
  * The Collection is used as a wrapper around a data array
  * it allows for the data to be accessed like an array or object.
+ * @template TKey of array-key
+ * @template T
+ *
+ * @implements IteratorAggregate<array-key, T>
  */
-class Collection implements ArrayAccess, Countable, IteratorAggregate {
+class Collection implements Countable, IteratorAggregate {
 	protected array $data = array();

 	public function __construct(array $initial = array()) {
@@ -50,7 +53,7 @@ class Collection implements ArrayAccess, Countable, IteratorAggregate {
 	 * return a reference so we can change e.g. sub arrays from this call
 	 *  => cannot use our own get() method.
 	 */
-	public function &__get(string $key) {
+	public function __get(string $key): mixed {
 		if (is_object($this->data[$key]) || $this->data[$key] === null) {
 			//only actual variables should be returned by reference
 			return $this->data[$key];
@@ -81,7 +84,7 @@ class Collection implements ArrayAccess, Countable, IteratorAggregate {
 	/**
 	 * @param string[] $which Array with keys that are requested
 	 */
-	public function getAll(?array $which = null): array {
+	public function all(?array $which = null): array {
 		if ($which !== null) {
 			return array_intersect_key($this->data, array_flip($which));
 		}
@@ -108,39 +111,6 @@ class Collection implements ArrayAccess, Countable, IteratorAggregate {
 		}
 	}

-	/**
-	 * {@inheritDoc}
-	 * @see self::__isset()
-	 */
-	public function offsetExists($offset): bool {
-		//use the isset method in order to return false for null value (the behaviour of isset())
-		return $this->__isset($offset);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * @see self::get()
-	 */
-	public function offsetGet($offset) {
-		return $this->get($offset);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * @see self::set()
-	 */
-	public function offsetSet($offset, $value): void {
-		$this->set($offset, $value);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 * @see self::remove()
-	 */
-	public function offsetUnset($offset): void {
-		$this->remove($offset);
-	}
-
 	public function remove(string $key): void {
 		unset($this->data[$key]);
 	}

diff --git a/a45ef12f46df6871a502077a9d865e0ea42b5461 b/8bbbfc56bd777fa230760f9db2564a6153bd1b77
index a45ef12..8bbbfc5 100644
--- a/a45ef12f46df6871a502077a9d865e0ea42b5461
+++ b/8bbbfc56bd777fa230760f9db2564a6153bd1b77
@@ -18,7 +18,7 @@ use function holonet\common\dot_key_set;
  *  e.g. toplevel.lowerlevel => $data['toplevel']['lowerlevel']
  *  e.g. "%app.name%-test" => $data['app']['name'] . "-test".
  */
-class Registry implements ArrayAccess {
+class Registry {
 	/**
 	 * @var array<string, mixed> $data Multilevel array with key=value pairs
 	 */
@@ -35,75 +35,35 @@ class Registry implements ArrayAccess {
 		$this->data = array();
 	}

-	/**
-	 * @see self::offsetGet()
-	 */
 	public function get(string $key, mixed $default = null): mixed {
-		return $this->offsetGet($key) ?? $default;
-	}
+		$value = dot_key_get($this->data, $key, separator: $this->separator);

-	/**
-	 * @see self::offsetExists()
-	 */
-	public function has(string $key): bool {
-		return $this->offsetExists($key);
+		return $this->replacePlaceholder($value) ?? $default;
 	}

-	/**
-	 * {@inheritDoc}
-	 */
-	public function offsetExists($offset): bool {
-		$parts = explode($this->separator, $offset);
+	public function has(string $key): bool {
+		$parts = explode($this->separator, $key);
 		$position = $this->data;
-		foreach ($parts as $sublevel) {
-			if (!isset($position[$sublevel])) {
+		foreach ($parts as $subLevel) {
+			if (!isset($position[$subLevel])) {
 				return false;
 			}
-			$position = $position[$sublevel];
+			$position = $position[$subLevel];
 		}

 		return true;
 	}

-	/**
-	 * {@inheritDoc}
-	 */
-	public function offsetGet($offset): mixed {
-		$value = dot_key_get($this->data, $offset, separator: $this->separator);
-
-		return $this->replacePlaceholder($value);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 */
-	public function offsetSet($offset, $value): void {
-		dot_key_set($this->data, $offset, $value, $this->separator);
-	}
-
-	/**
-	 * {@inheritDoc}
-	 */
-	public function offsetUnset($offset): void {
-		dot_key_set($this->data, $offset, null, $this->separator);
-	}
-
-	/**
-	 * @see self::offsetSet()
-	 */
 	public function set(string $key, $value): void {
-		$this->offsetSet($key, $value);
+		dot_key_set($this->data, $key, $value, $this->separator);
 	}

 	public function setAll(array $data): void {
 		$this->data = array_replace_recursive($this->data, $data);
 	}

-	/**
-	 * @see self::offsetUnset()
-	 */
 	public function unset(string $key): void {
-		$this->offsetUnset($key);
+		dot_key_set($this->data, $key, null, $this->separator);
 	}

 	/**

diff --git a/9cd09b5663fc7ee8ef75de35be5def0279e7b7a2 b/d3abc9f92256688586cc8184c20bd645b558828d
index 9cd09b5..d3abc9f 100644
--- a/9cd09b5663fc7ee8ef75de35be5def0279e7b7a2
+++ b/d3abc9f92256688586cc8184c20bd645b558828d
@@ -22,7 +22,7 @@ class ConfigRegistry extends Registry {
 	/**
 	 * @template T
 	 * Get an instance of a config dto class supplied by the user.
-	 * @param class-string<T>|T $cfgDto
+	 * @psalm-param class-string<T>|T $cfgDto
 	 * @return T
 	 */
 	public function asDto(string $configKey, string|object $cfgDto): object {
@@ -51,7 +51,7 @@ class ConfigRegistry extends Registry {
 	/**
 	 * @template T
 	 * Get a verified instance of a config dto class supplied by the user.
-	 * @param class-string<T>|T $cfgDto
+	 * @psalm-param class-string<T>|T $cfgDto
 	 * @return T
 	 */
 	public function verifiedDto(string $configKey, string|object $cfgDto): object {

diff --git a/a3a91deda75f58c115b6a114421878067ab6ab24 b/ca95b8884d1ed2a4e07e87642ed09b81350fabb1
index a3a91de..ca95b88 100644
--- a/a3a91deda75f58c115b6a114421878067ab6ab24
+++ b/ca95b8884d1ed2a4e07e87642ed09b81350fabb1
@@ -232,10 +232,10 @@ if (!function_exists(__NAMESPACE__.'\\dir_path')) {

 if (!function_exists(__NAMESPACE__.'\\str_lreplace')) {
 	/**
-	 * Replace the last occurence of a string inside the subject.
+	 * Replace the last occurrence of a string inside the subject.
 	 * Courtesy of https://stackoverflow.com/a/3835653.
 	 */
-	function str_lreplace($search, $replace, $subject) {
+	function str_lreplace(string $search, string $replace, string $subject): string {
 		$pos = mb_strrpos($subject, $search);

 		if ($pos !== false) {

diff --git a/8f27807563f695c567daef9563b091fc5557d4fa b/cf2d9dbb16aa2d33b6cfc46e01d50fa6af8dc728
index 8f27807..cf2d9db 100644
--- a/8f27807563f695c567daef9563b091fc5557d4fa
+++ b/cf2d9dbb16aa2d33b6cfc46e01d50fa6af8dc728
@@ -34,7 +34,7 @@ class Proof {

 	public function flat(): array {
 		$all = array();
-		array_walk_recursive($this->errors, function ($error) use (&$all): void { $all[] = $error; });
+		array_walk_recursive($this->errors, function (string $error) use (&$all): void { $all[] = $error; });

 		return $all;
 	}

diff --git a/2a5535d60af59ae09cbb23de6b3f048bd83839bb b/6c341bec8ad5a2425ba2b7e586fbe18d1b376df2
index 2a5535d..6c341be 100644
--- a/2a5535d60af59ae09cbb23de6b3f048bd83839bb
+++ b/6c341bec8ad5a2425ba2b7e586fbe18d1b376df2
@@ -12,8 +12,10 @@ namespace holonet\common\verifier\rules;
 use function holonet\common\stringify;

 abstract class Rule {
-	public function __construct(public ?string $message = null) {
-		$this->message ??= static::defaultMessage();
+	public string $message;
+
+	public function __construct(string $message = null) {
+		$this->message = $message ?? static::defaultMessage();
 	}

 	public static function defaultMessage(): string {

diff --git a/9f92571b617b7c98d18637656df09c9e29452e81 b/54fbfbb38efa0260c20bd1ff2c56f61e81f1e46e
index 9f92571..54fbfbb 100644
--- a/9f92571b617b7c98d18637656df09c9e29452e81
+++ b/54fbfbb38efa0260c20bd1ff2c56f61e81f1e46e
@@ -18,26 +18,6 @@ use PHPUnit\Framework\Attributes\CoversFunction;
 #[CoversFunction('holonet\common\dot_key_get')]
 #[CoversFunction('holonet\common\dot_key_set')]
 class RegistryTest extends TestCase {
-	public function testArrayAccessCalls(): void {
-		$registry = new Registry();
-
-		$data = array(
-			'array' => array(
-				'lowerval' => 'lower',
-				'arrayarray' => array(
-					'lowestval' => 'lowest'
-				)
-			)
-		);
-		$registry->setAll($data);
-
-		$this->assertSame('lowest', $registry['array.arrayarray.lowestval']);
-		$this->assertTrue(isset($registry['array.lowerval']));
-		$this->assertFalse(isset($registry['array.invalid']));
-		unset($registry['array.lowerval.arrayarray']);
-		$this->assertNull($registry['array.lowerval.arrayarray']);
-	}
-
 	public function testGetMultilevel(): void {
 		$registry = new Registry();

@@ -51,6 +31,7 @@ class RegistryTest extends TestCase {
 		);
 		$registry->setAll($data);

+		$this->assertFalse($registry->has('array.notexisting'));
 		$this->assertSame('lower', $registry->get('array.lowerval'));
 		$this->assertNull($registry->get('array.notexisting'));
 		$this->assertSame('lowest', $registry->get('array.arrayarray.lowestval'));