Add a regression test for a bug from an earlier iteration of the MethodHandles implementation

If a `javax.inject.Provider` was bound in a scope, we would enforce that it was a `com.google.inject.Provider` which was wrong.  This is due to logic in `MoreTypes.canonicalizeForKey` which canonicalizes `javax.inject.Provider` to the guice interface.

This behavior makes sense for injection points since guice only ever hands out `com.google.inject.Provider` instances but we don't always canonicalize them at every phase of injection which is what lead to the bug.  Now we no longer use `Dependency` objects to enforce types so we don't risk this issue anymore

PiperOrigin-RevId: 741129931

Author: lukesandberg

core/test/com/google/inject/BoundProviderTest.java

@@ -16,6 +16,8 @@
 
 package com.google.inject;
 
+import static com.google.inject.name.Names.named;
+
 import junit.framework.TestCase;
 
 /** @author [email protected] (Bob Lee) */
@@ -48,6 +50,9 @@ public void testSingletonFooProvider() throws CreationException {
               @Override
               protected void configure() {
                 bind(Foo.class).toProvider(SingletonFooProvider.class);
+                bind(Foo.class)
+                    .annotatedWith(named("javax"))
+                    .toProvider(JavaxInjectSingletonFooProvider.class);
               }
             });
 
@@ -59,6 +64,16 @@ protected void configure() {
     assertNotNull(a.bar);
     assertNotNull(b.bar);
     assertSame(a.bar, b.bar);
+
+    var javaxKey = Key.get(Foo.class, named("javax"));
+    a = injector.getInstance(javaxKey);
+    b = injector.getInstance(javaxKey);
+
+    assertEquals(0, a.i);
+    assertEquals(1, b.i);
+    assertNotNull(a.bar);
+    assertNotNull(b.bar);
+    assertSame(a.bar, b.bar);
   }
 
   static class Bar {}
@@ -105,4 +120,25 @@ public Foo get() {
       return new Foo(this.bar, count++);
     }
   }
+
+  // Use a jakarta.inject.Provider as well.  Dependency.get() always canonicalizes the jakarta.inject
+  // provider to the Guice provider, which at one point caused a bug in the MethodHandle
+  // implementation which attempted to enforce types derived from the
+  // Dependency objects
+  @Singleton
+  static class JavaxInjectSingletonFooProvider implements jakarta.inject.Provider<Foo> {
+
+    final Bar bar;
+    int count = 0;
+
+    @Inject
+    JavaxInjectSingletonFooProvider(Bar bar) {
+      this.bar = bar;
+    }
+
+    @Override
+    public Foo get() {
+      return new Foo(this.bar, count++);
+    }
+  }
 }