Clear, communicative naming is important in code. It helps maintainers and API users understand the intentions for and uses of a unit of code. Using "exception" in the name of a class that does not extend Exception or one of its subclasses is a clear violation of the expectation that a class' name will indicate what it is and/or does.

Noncompliant Code Example

class FruitException {  // Noncompliant; this has nothing to do with Exception
  private $expected;
  private $unusualCharacteristics;
  private $appropriateForCommercialExploitation;
  // ...
}

class CarException {  // Noncompliant; the extends clause was forgotten?
  public function __construct(string message, Throwable cause) {
  // ...

Compliant Solution

class FruitSport {
  private $expected;
  private $unusualCharacteristics;
  private $appropriateForCommercialExploitation;
  // ...
}

class CarException extends Exception {
  public function __construct(string message, Throwable cause) {
  // ...