Adjust retrieval of java.time package name

Author: Marcono1234

gson/src/main/java/com/google/gson/internal/bind/JavaTimeTypeAdapters.java

@@ -429,21 +429,17 @@ private static <T> T requireNonNullField(T field, String fieldName, JsonReader r
    * href="https://developer.android.com/studio/write/java8-support#library-desugaring">API
    * desugaring</a>.
    */
-  private static String javaTimePackage() {
+  static String javaTimePackage() {
     try {
       // Use arbitrary java.time.* class here, one which is quite simple and does not refer to many
       // other classes
       String className = DateTimeException.class.getName();
       int packageEnd = className.lastIndexOf('.');
-      // To be safe, account for no '.' in package name (quite unlikely though) in case of Android
-      // API desugaring
-      if (packageEnd != -1) {
-        return className.substring(0, packageEnd + 1);
-      }
+      return className.substring(0, packageEnd + 1);
     } catch (LinkageError ignored) {
       // java.time.* classes are probably not available
+      return null;
     }
-    return null;
   }
 
   private static class AdapterFactory implements TypeAdapterFactory {

gson/src/test/java/com/google/gson/internal/bind/JavaTimeTypeAdaptersTest.java

@@ -0,0 +1,18 @@
+package com.google.gson.internal.bind;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import org.junit.Test;
+
+/** Functional tests are in {@link com.google.gson.functional.JavaTimeTest}. */
+public class JavaTimeTypeAdaptersTest {
+  @Test
+  public void testJavaTimePackage() {
+    assertThat(JavaTimeTypeAdapters.javaTimePackage()).isEqualTo("java.time.");
+  }
+
+  @Test
+  public void testGetFactory() {
+    assertThat(new JavaTimeTypeAdapters().get()).isNotNull();
+  }
+}