diff --git a/core/lib/Drupal/Component/ProxyBuilder/ProxyBuilder.php b/core/lib/Drupal/Component/ProxyBuilder/ProxyBuilder.php
index f785336..26583fa 100644
--- a/core/lib/Drupal/Component/ProxyBuilder/ProxyBuilder.php
+++ b/core/lib/Drupal/Component/ProxyBuilder/ProxyBuilder.php
@@ -7,42 +7,63 @@
 
 namespace Drupal\Component\ProxyBuilder;
 
+/**
+ * Generates the string representation of the proxy service.
+ */
 class ProxyBuilder {
 
+  /**
+   * Generates the used proxy class name from a given class name.
+   *
+   * @param string $class_name
+   *   The class name of the actual service.
+   *
+   * @return string
+   *   The class name of the proxy.
+   */
   public function buildProxyClassName($class_name) {
     return str_replace('\\', '_', $class_name) . '_Proxy';
   }
 
+  /**
+   * Builds a proxy class string.
+   *
+   * @param string $class_name
+   *   The class name of the actual service.
+   *
+   * @return string
+   *   The full string with namespace class and methods.
+   */
   public function build($class_name) {
     $reflection = new \ReflectionClass($class_name);
 
     // The actual class;
-    $output = 'class ' . $this->buildProxyClassName($class_name);
+    $output = '';
+    $class_start = 'class ' . $this->buildProxyClassName($class_name);
 
     if ($interfaces = $reflection->getInterfaceNames()) {
-//      foreach ($interfaces as &$interface) {
-//        $interface = '\\' . $interface;
-//      }
       $output .= ' implements ' . implode(', ', $interfaces);
     }
 
     $output .= " {\n";
 
     // Add the variables.
-    $output .= "\n /**
-  * @var string
-  */
-  protected \$serviceId;\n
+    $output .= "\n/**
+ * @var string
+ */
+protected \$serviceId;
 
-  /**
-   * @var \\$class_name
-   */
-  protected \$service;\n";
+/**
+ * @var \\$class_name
+ */
+protected \$service;\n\n";
 
+    // Add all the methods.
     $methods = [];
     $methods[] = $this->buildConstructorMethod();
     $methods[] = $this->buildLazyLoadItselfMethod();
 
+    // Add all the methods of the proxied service.
     $reflection_methods = $reflection->getMethods();
 
     foreach ($reflection_methods as $method) {
@@ -57,11 +78,19 @@ public function build($class_name) {
 
     $output .= implode("\n", $methods);
 
-    $output .= "\n}\n";
+    // Intend the output.
+    $output = implode("\n", array_map(function($value) {
+      return "  $value";
+    }, explode("\n", $output)));
 
-    return $output;
+    return $class_start . $output . "\n\n}\n";
   }
 
+  /**
+   * Generates the string for the method which loads the actual service.
+   *
+   * @return string
+   */
   protected function buildLazyLoadItselfMethod() {
     $output = "protected function lazyLoadItself() {
   if (!isset(\$this->service)) {
@@ -75,6 +104,14 @@ protected function buildLazyLoadItselfMethod() {
     return $output;
   }
 
+  /**
+   * Generates the string representation of a single method: signature, body.
+   *
+   * @param \ReflectionMethod $reflection_method
+   *   A reflection method for the method.
+   *
+   * @return string
+   */
   protected function buildMethod(\ReflectionMethod $reflection_method) {
 
     $parameters = [];
@@ -83,10 +120,9 @@ protected function buildMethod(\ReflectionMethod $reflection_method) {
     }
 
     $function_name = $reflection_method->getName();
-    $signature_line = 'public function ' . $function_name . '(';
 
+    $signature_line = 'public function ' . $function_name . '(';
     $signature_line .= implode(', ', $parameters);
-
     $signature_line .= ')';
 
     $output = $signature_line . ' {' . "\n";
@@ -97,14 +133,26 @@ protected function buildMethod(\ReflectionMethod $reflection_method) {
     return $output;
   }
 
+  /**
+   * Builds a string for a single parameter of a method.
+   *
+   * @param \ReflectionParameter $parameter
+   *   A reflection object of the parameter.
+   *
+   * @return string
+   */
   protected function buildParameter(\ReflectionParameter $parameter) {
     $parameter_string = '';
+
     if ($parameter->isArray()) {
       $parameter_string .= 'array ';
     }
-    if ($parameter->isCallable()) {
+    elseif ($parameter->isCallable()) {
       $parameter_string .= 'callable ';
     }
+    elseif ($class = $parameter->getClass()) {
+      $parameter_string .= $class->getName() . ' ';
+    }
 
     if ($parameter->isPassedByReference()) {
       $parameter_string .= '&';
@@ -120,6 +168,14 @@ protected function buildParameter(\ReflectionParameter $parameter) {
     return $parameter_string;
   }
 
+  /**
+   * Builds the body of a wrapped method.
+   *
+   * @param \ReflectionMethod $reflection_method
+   *   A reflection method for the method.
+   *
+   * @return string
+   */
   protected function buildMethodBody(\ReflectionMethod $reflection_method) {
     $output = '';
 
@@ -138,6 +194,11 @@ protected function buildMethodBody(\ReflectionMethod $reflection_method) {
     return $output;
   }
 
+  /**
+   * Builds the constructor used to inject the actual service ID.
+   *
+   * @return string
+   */
   protected function buildConstructorMethod() {
     $output = 'public function __construct($service_id) {
   $this->serviceId = $service_id;
diff --git a/core/lib/Drupal/Component/ProxyBuilder/ProxyDumper.php b/core/lib/Drupal/Component/ProxyBuilder/ProxyDumper.php
index fb125d8..07e30ee 100644
--- a/core/lib/Drupal/Component/ProxyBuilder/ProxyDumper.php
+++ b/core/lib/Drupal/Component/ProxyBuilder/ProxyDumper.php
@@ -10,6 +10,9 @@
 use Symfony\Component\DependencyInjection\Definition;
 use Symfony\Component\DependencyInjection\LazyProxy\PhpDumper\DumperInterface;
 
+/**
+ * Dumps the proxy service into the dumped PHP container file.
+ */
 class ProxyDumper implements DumperInterface {
 
   /**
@@ -35,6 +38,9 @@ public function isProxyCandidate(Definition $definition) {
    */
   public function getProxyFactoryCode(Definition $definition, $id) {
     $id = var_export($id, TRUE);
+    // Note: the specific get method is called initially with $lazyLoad=TRUE;
+    // When you want to retrieve the actual service, the code generated in
+    // ProxyBuilder calls the method with lazy loading disabled.
     $output = "        if (\$lazyLoad) {\n";
     $output .= "            return \$this->services[$id] = new " . $this->builder->buildProxyClassName($definition->getClass()) . '(' . $id . ");\n";
     $output .= "        }\n";