Processes the ContainerBuilder to validate the Definition.
ContainerBuilder $container:
RuntimeException When the Definition is invalid
Overrides CompilerPassInterface::process
public function process(ContainerBuilder $container) {
  foreach ($container
    ->getDefinitions() as $id => $definition) {
    // synthetic service is public
    if ($definition
      ->isSynthetic() && !$definition
      ->isPublic()) {
      throw new RuntimeException(sprintf('A synthetic service ("%s") must be public.', $id));
    }
    // synthetic service has non-prototype scope
    if ($definition
      ->isSynthetic() && ContainerInterface::SCOPE_PROTOTYPE === $definition
      ->getScope()) {
      throw new RuntimeException(sprintf('A synthetic service ("%s") cannot be of scope "prototype".', $id));
    }
    // non-synthetic, non-abstract service has class
    if (!$definition
      ->isAbstract() && !$definition
      ->isSynthetic() && !$definition
      ->getClass()) {
      if ($definition
        ->getFactoryClass() || $definition
        ->getFactoryService()) {
        throw new RuntimeException(sprintf('Please add the class to service "%s" even if it is constructed by a factory ' . 'since we might need to add method calls based on compile-time checks.', $id));
      }
      throw new RuntimeException(sprintf('The definition for "%s" has no class. If you intend to inject ' . 'this service dynamically at runtime, please mark it as synthetic=true. ' . 'If this is an abstract definition solely used by child definitions, ' . 'please add abstract=true, otherwise specify a class to get rid of this error.', $id));
    }
  }
}