Avoid varargs warnings using @SafeVarags in generated code.

The annotation can only be added to final methods, so we have to use
@SuppessWarnings for RequestOptions instead. As a result callers of
transforms() will have to suppress the warning on their end as well.

Fixes #2383.

annotation/compiler/src/main/java/com/bumptech/glide/annotation/compiler/RequestBuilderGenerator.java

@@ -287,7 +287,18 @@ final class RequestBuilderGenerator {
     return MethodSpec.methodBuilder(requestOptionMethod.name)
         .addJavadoc(
             processorUtil.generateSeeMethodJavadoc(requestOptionsClassName, requestOptionMethod))
-        .addModifiers(Modifier.PUBLIC)
+        .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+        .varargs(requestOptionMethod.varargs)
+        .addAnnotations(
+            FluentIterable.from(requestOptionMethod.annotations)
+                .filter(new Predicate<AnnotationSpec>() {
+                  @Override
+                  public boolean apply(AnnotationSpec input) {
+                    return !input.type.equals(TypeName.get(Override.class));
+                  }
+                })
+                .toList()
+        )
         .addTypeVariables(requestOptionMethod.typeVariables)
         .addParameters(requestOptionMethod.parameters)
         .returns(generatedRequestBuilderOfTranscodeType)

annotation/compiler/src/main/java/com/bumptech/glide/annotation/compiler/RequestOptionsGenerator.java

@@ -190,8 +190,9 @@ final class RequestOptionsGenerator {
   }
 
   private MethodSpec generateRequestOptionOverride(ExecutableElement methodToOverride) {
-    return MethodSpec.overriding(methodToOverride)
+    MethodSpec.Builder result = MethodSpec.overriding(methodToOverride)
         .returns(glideOptionsName)
+        .addModifiers(Modifier.FINAL)
         .addCode(CodeBlock.builder()
             .add("return ($T) super.$N(", glideOptionsName, methodToOverride.getSimpleName())
             .add(FluentIterable.from(methodToOverride.getParameters())
@@ -203,8 +204,15 @@ final class RequestOptionsGenerator {
                 })
                 .join(Joiner.on(", ")))
             .add(");\n")
-            .build())
-        .build();
+            .build());
+
+    if (methodToOverride.getSimpleName().toString().equals("transforms")) {
+      result.addAnnotation(
+          AnnotationSpec.builder(SafeVarargs.class)
+              .build());
+    }
+
+    return result.build();
   }
 
   private List<MethodAndStaticVar> generateMethodsForRequestOptionsExtension(

library/src/main/java/com/bumptech/glide/request/RequestOptions.java

@@ -1005,7 +1005,7 @@ public class RequestOptions implements Cloneable {
    * @see #optionalTransform(Transformation)
    * @see #optionalTransform(Class, Transformation)
    */
-  @SuppressWarnings("unchecked")
+  @SuppressWarnings({"unchecked", "varargs"})
   public RequestOptions transforms(@NonNull Transformation<Bitmap>... transformations) {
     if (isAutoCloneEnabled) {
       return clone().transforms(transformations);