Re-enable shadowed, overridden @Test methods

Due to a bug (or "unintentional feature") in JUnit 4, overridden test
methods not annotated with @Test are still executed as test methods;
however, JUnit Jupiter does not support that. Thus, prior to this
commit, some overridden test methods in spring-core were no longer
executed after the migration from JUnit 4 to JUnit Jupiter.

This commit addresses this issue for such known use cases, but there
are likely other such use cases within Spring's test suite.

See gh-23451

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

@@ -55,6 +55,7 @@ class ByteArrayEncoderTests extends AbstractEncoderTestCase<ByteArrayEncoder> {
 	}
 
 	@Override
+	@Test
 	public void encode() {
 		Flux<byte[]> input = Flux.just(this.fooBytes, this.barBytes);
 
@@ -63,4 +64,5 @@ class ByteArrayEncoderTests extends AbstractEncoderTestCase<ByteArrayEncoder> {
 				.consumeNextWith(expectBytes(this.barBytes))
 				.verifyComplete());
 	}
+
 }

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

@@ -46,6 +46,7 @@ class CharSequenceEncoderTests extends AbstractEncoderTestCase<CharSequenceEncod
 
 
 	@Override
+	@Test
 	public void canEncode() throws Exception {
 		assertThat(this.encoder.canEncode(ResolvableType.forClass(String.class),
 				MimeTypeUtils.TEXT_PLAIN)).isTrue();
@@ -63,6 +64,7 @@ class CharSequenceEncoderTests extends AbstractEncoderTestCase<CharSequenceEncod
 	}
 
 	@Override
+	@Test
 	public void encode() {
 		Flux<CharSequence> input = Flux.just(this.foo, this.bar);
 

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

@@ -55,6 +55,7 @@ class DataBufferDecoderTests extends AbstractDecoderTestCase<DataBufferDecoder>
 	}
 
 	@Override
+	@Test
 	public void decode() {
 		Flux<DataBuffer> input = Flux.just(
 				this.bufferFactory.wrap(this.fooBytes),
@@ -67,6 +68,7 @@ class DataBufferDecoderTests extends AbstractDecoderTestCase<DataBufferDecoder>
 	}
 
 	@Override
+	@Test
 	public void decodeToMono() throws Exception {
 		Flux<DataBuffer> input = Flux.concat(
 				dataBuffer(this.fooBytes),

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

@@ -57,6 +57,7 @@ class DataBufferEncoderTests extends AbstractEncoderTestCase<DataBufferEncoder>
 	}
 
 	@Override
+	@Test
 	public void encode() throws Exception {
 		Flux<DataBuffer> input = Flux.just(this.fooBytes, this.barBytes)
 				.flatMap(bytes -> Mono.defer(() -> {

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

@@ -79,6 +79,7 @@ class ResourceDecoderTests extends AbstractDecoderTestCase<ResourceDecoder> {
 	}
 
 	@Override
+	@Test
 	public void decodeToMono() {
 		Flux<DataBuffer> input = Flux.concat(
 				dataBuffer(this.fooBytes),

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

@@ -64,6 +64,7 @@ class ResourceEncoderTests extends AbstractEncoderTestCase<ResourceEncoder> {
 	}
 
 	@Override
+	@Test
 	public void encode() {
 		Flux<Resource> input = Flux.just(new ByteArrayResource(this.bytes));
 

spring-core/src/test/java/org/springframework/core/type/classreading/AnnotationMetadataReadingVisitorTests.java

@@ -19,6 +19,8 @@ package org.springframework.core.type.classreading;
 import java.io.BufferedInputStream;
 import java.io.InputStream;
 
+import org.junit.jupiter.api.Test;
+
 import org.springframework.asm.ClassReader;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
@@ -61,6 +63,7 @@ class AnnotationMetadataReadingVisitorTests extends AbstractAnnotationMetadataTe
 	}
 
 	@Override
+	@Test
 	public void getAnnotationsReturnsDirectAnnotations() {
 		assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(
 				super::getAnnotationsReturnsDirectAnnotations);

spring-core/src/test/java/org/springframework/core/type/classreading/MethodMetadataReadingVisitorTests.java

@@ -19,6 +19,8 @@ package org.springframework.core.type.classreading;
 import java.io.BufferedInputStream;
 import java.io.InputStream;
 
+import org.junit.jupiter.api.Test;
+
 import org.springframework.asm.ClassReader;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
@@ -61,6 +63,7 @@ class MethodMetadataReadingVisitorTests extends AbstractMethodMetadataTests {
 	}
 
 	@Override
+	@Test
 	public void getAnnotationsReturnsDirectAnnotations() {
 		assertThatExceptionOfType(UnsupportedOperationException.class).isThrownBy(
 				super::getAnnotationsReturnsDirectAnnotations);