Fix #4083 - namespace docblock method classes the proper way

src/Psalm/Internal/Analyzer/CommentAnalyzer.php

@@ -1123,7 +1123,9 @@ class CommentAnalyzer
                                 'Badly-formatted @method string ' . $method_entry . ' - ' . $e
                             );
                         }
-                        $docblock_lines[] = '@param \\' . $param_type . ' '
+
+                        $param_type_string = $param_type->toNamespacedString('\\', [], null, false);
+                        $docblock_lines[] = '@param ' . $param_type_string . ' '
                             . ($method_tree_child->variadic ? '...' : '')
                             . $method_tree_child->name;
                     }

tests/MagicMethodAnnotationTest.php

@@ -694,6 +694,21 @@ class MagicMethodAnnotationTest extends TestCase
                         (new \Foo\G)->randomInt();
                     }'
             ],
+            'namespacedUnion' => [
+                '<?php
+                    namespace Foo;
+
+                    /**
+                     * @method string bar(\DateTimeInterface|\DateInterval|self $a, Cache|\Exception $e)
+                     */
+                    class Cache {
+                        public function __call(string $method, array $args) {
+                            return $method;
+                        }
+                    }
+
+                    (new Cache)->bar(new \DateTime(), new Cache());'
+            ],
         ];
     }