Document that this is a fluent API

Author: sebastianbergmann

src/Framework/MockObject/Runtime/Builder/InvocationStubber.php

@@ -19,22 +19,45 @@ interface InvocationStubber
 {
     public function will(Stub $stub): Identity;
 
+    /**
+     * @return $this
+     */
     public function willReturn(mixed $value, mixed ...$nextValues): self;
 
+    /**
+     * @return $this
+     */
     public function willReturnReference(mixed &$reference): self;
 
     /**
      * @param array<int, array<int, mixed>> $valueMap
+     *
+     * @return $this
      */
     public function willReturnMap(array $valueMap): self;
 
+    /**
+     * @return $this
+     */
     public function willReturnArgument(int $argumentIndex): self;
 
+    /**
+     * @return $this
+     */
     public function willReturnCallback(callable $callback): self;
 
+    /**
+     * @return $this
+     */
     public function willReturnSelf(): self;
 
+    /**
+     * @return $this
+     */
     public function willReturnOnConsecutiveCalls(mixed ...$values): self;
 
+    /**
+     * @return $this
+     */
     public function willThrowException(Throwable $exception): self;
 }