Clean up warnings and dead code in spring-core module

spring-core/src/main/java/org/springframework/core/codec/ResourceEncoder.java

@@ -18,7 +18,6 @@ package org.springframework.core.codec;
 
 import java.io.IOException;
 import java.util.Map;
-import java.util.OptionalLong;
 
 import reactor.core.publisher.Flux;
 

spring-core/src/main/java/org/springframework/core/codec/ResourceRegionEncoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,7 +71,6 @@ public class ResourceRegionEncoder extends AbstractEncoder<ResourceRegion> {
 	}
 
 	@Override
-	@SuppressWarnings("unchecked")
 	public Flux<DataBuffer> encode(Publisher<? extends ResourceRegion> inputStream,
 			DataBufferFactory bufferFactory, ResolvableType elementType, @Nullable MimeType mimeType,
 			@Nullable Map<String, Object> hints) {