Fix generated proguard rule

bug: 69869016
Test: none
Change-Id: I170b18145dbe2fa47e0c95749c4ef4eb83ab9626
diff --git a/lifecycle/compiler/src/main/kotlin/android/arch/lifecycle/writer.kt b/lifecycle/compiler/src/main/kotlin/android/arch/lifecycle/writer.kt
index 8510eef..81345ff 100644
--- a/lifecycle/compiler/src/main/kotlin/android/arch/lifecycle/writer.kt
+++ b/lifecycle/compiler/src/main/kotlin/android/arch/lifecycle/writer.kt
@@ -148,10 +148,11 @@
     val adapterClass = type.getPackageQName() + "." + getAdapterName(type)
     val observerClass = type.toString()
     val keepRule = """# Generated keep rule for Lifecycle observer adapter.
+        |-if class $observerClass {
+        |    <init>(...);
+        |}
         |-keep class $adapterClass {
-        |   ifused class $observerClass {
-        |       <init>(...);
-        |   };
+        |    <init>(...);
         |}
         |""".trimMargin()