Clean up warnings and polish tests

This commit also modifies ResourceWebHandlerTests.getResourceFromFileSystem()
so that it passes in the IDE.

spring-core/src/main/java/org/springframework/core/io/buffer/DefaultDataBuffer.java

@@ -506,6 +506,7 @@ public class DefaultDataBuffer implements DataBuffer {
 		}
 
 		@Override
+		@SuppressWarnings("deprecation")
 		public DefaultDataBuffer capacity(int newCapacity) {
 			throw new UnsupportedOperationException("Changing the capacity of a sliced buffer is not supported");
 		}

spring-core/src/test/java/org/springframework/core/codec/Netty5BufferEncoderTests.java

@@ -42,8 +42,8 @@ class Netty5BufferEncoderTests extends AbstractEncoderTests<Netty5BufferEncoder>
 		super(new Netty5BufferEncoder());
 	}
 
-	@Override
 	@Test
+	@Override
 	public void canEncode() {
 		assertThat(this.encoder.canEncode(ResolvableType.forClass(Buffer.class),
 				MimeTypeUtils.TEXT_PLAIN)).isTrue();
@@ -56,8 +56,9 @@ class Netty5BufferEncoderTests extends AbstractEncoderTests<Netty5BufferEncoder>
 		assertThat(this.encoder.canEncode(ResolvableType.NONE, null)).isFalse();
 	}
 
-	@Override
 	@Test
+	@Override
+	@SuppressWarnings("resource")
 	public void encode() {
 		Flux<Buffer> input = Flux.just(this.fooBytes, this.barBytes)
 				.map(DefaultBufferAllocators.preferredAllocator()::copyOf);
@@ -67,4 +68,5 @@ class Netty5BufferEncoderTests extends AbstractEncoderTests<Netty5BufferEncoder>
 				.consumeNextWith(expectBytes(this.barBytes))
 				.verifyComplete());
 	}
+
 }

spring-core/src/test/java/org/springframework/core/io/buffer/DataBufferTests.java

@@ -389,6 +389,7 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 	}
 
 	@ParameterizedDataBufferAllocatingTest
+	@SuppressWarnings("deprecation")
 	void increaseCapacity(DataBufferFactory bufferFactory) {
 		super.bufferFactory = bufferFactory;
 
@@ -402,6 +403,7 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 	}
 
 	@ParameterizedDataBufferAllocatingTest
+	@SuppressWarnings("deprecation")
 	void decreaseCapacityLowReadPosition(DataBufferFactory bufferFactory) {
 		assumeFalse(bufferFactory instanceof Netty5DataBufferFactory,
 				"Netty 5 does not support decreasing the capacity");
@@ -417,6 +419,7 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 	}
 
 	@ParameterizedDataBufferAllocatingTest
+	@SuppressWarnings("deprecation")
 	void decreaseCapacityHighReadPosition(DataBufferFactory bufferFactory) {
 		assumeFalse(bufferFactory instanceof Netty5DataBufferFactory,
 				"Netty 5 does not support decreasing the capacity");
@@ -433,13 +436,13 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 	}
 
 	@ParameterizedDataBufferAllocatingTest
+	@SuppressWarnings("deprecation")
 	void capacityLessThanZero(DataBufferFactory bufferFactory) {
 		super.bufferFactory = bufferFactory;
 
 		DataBuffer buffer = createDataBuffer(1);
 		try {
-			assertThatIllegalArgumentException().isThrownBy(() ->
-					buffer.capacity(-1));
+			assertThatIllegalArgumentException().isThrownBy(() -> buffer.capacity(-1));
 		}
 		finally {
 			release(buffer);
@@ -754,6 +757,7 @@ class DataBufferTests extends AbstractDataBufferAllocatingTests {
 	}
 
 	@ParameterizedDataBufferAllocatingTest
+	@SuppressWarnings("deprecation")
 	void spr16351(DataBufferFactory bufferFactory) {
 		super.bufferFactory = bufferFactory;
 

spring-core/src/test/java/org/springframework/core/io/buffer/LeakAwareDataBufferFactoryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2022 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.
@@ -32,11 +32,11 @@ class LeakAwareDataBufferFactoryTests {
 
 
 	@Test
+	@SuppressWarnings("deprecation")
 	void leak() {
 		DataBuffer dataBuffer = this.bufferFactory.allocateBuffer();
 		try {
-			assertThatExceptionOfType(AssertionError.class).isThrownBy(
-					this.bufferFactory::checkForLeaks);
+			assertThatExceptionOfType(AssertionError.class).isThrownBy(this.bufferFactory::checkForLeaks);
 		}
 		finally {
 			release(dataBuffer);
@@ -45,7 +45,7 @@ class LeakAwareDataBufferFactoryTests {
 
 	@Test
 	void noLeak() {
-		DataBuffer dataBuffer = this.bufferFactory.allocateBuffer();
+		DataBuffer dataBuffer = this.bufferFactory.allocateBuffer(256);
 		release(dataBuffer);
 		this.bufferFactory.checkForLeaks();
 	}

spring-core/src/testFixtures/java/org/springframework/core/testfixture/io/buffer/LeakAwareDataBufferFactory.java

@@ -99,7 +99,7 @@ public class LeakAwareDataBufferFactory implements DataBufferFactory {
 			List<AssertionError> errors = this.created.stream()
 					.filter(LeakAwareDataBuffer::isAllocated)
 					.map(LeakAwareDataBuffer::leakError)
-					.collect(Collectors.toList());
+					.toList();
 
 			errors.forEach(it -> logger.error("Leaked error: ", it));
 			throw new AssertionError(errors.size() + " buffer leaks detected (see logs above)");