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Add ConversionService support for ByteBuffers
Add ByteBufferConverter that is registered by default with the DefaultConversionService. Allows conversion from/to a ByteBuffer and byte[] or to any type that can be converted via a byte[]. Issue: SPR-10712
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‎spring-core/src/main/java/org/springframework/core/convert/support/ByteBufferConverter.java

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/*
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* Copyright 2002-2013 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.core.convert.support;
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import java.nio.ByteBuffer;
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import java.util.Collections;
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import java.util.HashSet;
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import java.util.Set;
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import org.springframework.core.convert.ConversionService;
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import org.springframework.core.convert.TypeDescriptor;
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import org.springframework.core.convert.converter.ConditionalGenericConverter;
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/**
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* Converts a {@link ByteBuffer} directly to and from {@code byte[]}s and indirectly to
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* any type that the {@link ConversionService} support via {@code byte[]}.
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*
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* @author Phillip Webb
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*/
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public class ByteBufferConverter implements ConditionalGenericConverter {
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private static final TypeDescriptor BYTE_BUFFER_TYPE = TypeDescriptor.valueOf(ByteBuffer.class);
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private static final TypeDescriptor BYTE_ARRAY_TYPE = TypeDescriptor.valueOf(byte[].class);
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private static final Set<ConvertiblePair> CONVERTIBLE_PAIRS;
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static {
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Set<ConvertiblePair> convertiblePairs = new HashSet<ConvertiblePair>();
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convertiblePairs.add(new ConvertiblePair(ByteBuffer.class, Object.class));
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convertiblePairs.add(new ConvertiblePair(Object.class, ByteBuffer.class));
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CONVERTIBLE_PAIRS = Collections.unmodifiableSet(convertiblePairs);
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}
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private ConversionService conversionService;
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public ByteBufferConverter(ConversionService conversionService) {
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this.conversionService = conversionService;
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}
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@Override
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public Set<ConvertiblePair> getConvertibleTypes() {
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return CONVERTIBLE_PAIRS;
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}
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@Override
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public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
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if (sourceType.isAssignableTo(BYTE_BUFFER_TYPE)) {
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return matchesFromByteBuffer(targetType);
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}
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if (targetType.isAssignableTo(BYTE_BUFFER_TYPE)) {
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return matchesToByteBuffer(sourceType);
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}
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return false;
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}
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private boolean matchesFromByteBuffer(TypeDescriptor targetType) {
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return (targetType.isAssignableTo(BYTE_ARRAY_TYPE) || this.conversionService.canConvert(
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BYTE_ARRAY_TYPE, targetType));
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}
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private boolean matchesToByteBuffer(TypeDescriptor sourceType) {
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return (sourceType.isAssignableTo(BYTE_ARRAY_TYPE) || this.conversionService.canConvert(
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sourceType, BYTE_ARRAY_TYPE));
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}
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@Override
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public Object convert(Object source, TypeDescriptor sourceType,
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TypeDescriptor targetType) {
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if (sourceType.isAssignableTo(BYTE_BUFFER_TYPE)) {
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return convertFromByteBuffer((ByteBuffer) source, targetType);
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}
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if (targetType.isAssignableTo(BYTE_BUFFER_TYPE)) {
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return convertToByteBuffer(source, sourceType);
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}
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// Should not happen
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throw new IllegalStateException("Unexpected source/target types");
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}
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private Object convertFromByteBuffer(ByteBuffer source, TypeDescriptor targetType) {
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byte[] bytes = new byte[source.remaining()];
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source.get(bytes);
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if (targetType.isAssignableTo(BYTE_ARRAY_TYPE)) {
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return bytes;
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}
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return this.conversionService.convert(bytes, BYTE_ARRAY_TYPE, targetType);
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}
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private Object convertToByteBuffer(Object source, TypeDescriptor sourceType) {
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byte[] bytes = (byte[]) (source instanceof byte[] ? source
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: this.conversionService.convert(source, sourceType, BYTE_ARRAY_TYPE));
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ByteBuffer byteBuffer = ByteBuffer.allocate(bytes.length);
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byteBuffer.put(bytes);
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byteBuffer.rewind();
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return byteBuffer;
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}
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}

‎spring-core/src/main/java/org/springframework/core/convert/support/DefaultConversionService.java

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public static void addDefaultConverters(ConverterRegistry converterRegistry) {
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addScalarConverters(converterRegistry);
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addCollectionConverters(converterRegistry);
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addBinaryConverters(converterRegistry);
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addFallbackConverters(converterRegistry);
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}
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converterRegistry.addConverter(new ObjectToCollectionConverter(conversionService));
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}
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private static void addBinaryConverters(ConverterRegistry converterRegistry) {
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ConversionService conversionService = (ConversionService) converterRegistry;
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converterRegistry.addConverter(new ByteBufferConverter(conversionService));
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}
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private static void addFallbackConverters(ConverterRegistry converterRegistry) {
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ConversionService conversionService = (ConversionService) converterRegistry;
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converterRegistry.addConverter(new ObjectToObjectConverter());

‎spring-core/src/test/java/org/springframework/core/convert/support/ByteBufferConverterTests.java

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/*
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* Copyright 2002-2013 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.springframework.core.convert.support;
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import java.nio.ByteBuffer;
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import org.junit.Before;
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import org.junit.Test;
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import org.springframework.core.convert.converter.Converter;
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import static org.hamcrest.Matchers.*;
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import static org.junit.Assert.*;
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/**
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* Tests for {@link ByteBufferConverter}.
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*
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* @author Phillip Webb
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*/
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public class ByteBufferConverterTests {
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private GenericConversionService conversionService;
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@Before
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public void setup() {
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this.conversionService = new GenericConversionService();
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this.conversionService.addConverter(new ByteBufferConverter(conversionService));
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this.conversionService.addConverter(new ByteArrayToOtherTypeConverter());
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this.conversionService.addConverter(new OtherTypeToByteArrayConverter());
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}
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@Test
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public void byteArrayToByteBuffer() throws Exception {
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byte[] bytes = new byte[] { 1, 2, 3 };
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ByteBuffer convert = this.conversionService.convert(bytes, ByteBuffer.class);
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assertThat(bytes, not(sameInstance(convert.array())));
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assertThat(bytes, equalTo(convert.array()));
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}
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@Test
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public void byteBufferToByteArray() throws Exception {
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byte[] bytes = new byte[] { 1, 2, 3 };
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ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
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byte[] convert = this.conversionService.convert(byteBuffer, byte[].class);
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assertThat(bytes, not(sameInstance(convert)));
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assertThat(bytes, equalTo(convert));
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}
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@Test
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public void byteBufferToOtherType() throws Exception {
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byte[] bytes = new byte[] { 1, 2, 3 };
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ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
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OtherType convert = this.conversionService.convert(byteBuffer, OtherType.class);
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assertThat(bytes, not(sameInstance(convert.bytes)));
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assertThat(bytes, equalTo(convert.bytes));
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}
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@Test
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public void otherTypeToByteBuffer() throws Exception {
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byte[] bytes = new byte[] { 1, 2, 3 };
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OtherType otherType = new OtherType(bytes);
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ByteBuffer convert = this.conversionService.convert(otherType, ByteBuffer.class);
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assertThat(bytes, not(sameInstance(convert.array())));
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assertThat(bytes, equalTo(convert.array()));
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}
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private static class OtherType {
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private byte[] bytes;
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public OtherType(byte[] bytes) {
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this.bytes = bytes;
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}
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}
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private static class ByteArrayToOtherTypeConverter implements
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Converter<byte[], OtherType> {
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@Override
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public OtherType convert(byte[] source) {
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return new OtherType(source);
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}
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}
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private static class OtherTypeToByteArrayConverter implements
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Converter<OtherType, byte[]> {
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@Override
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public byte[] convert(OtherType source) {
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return source.bytes;
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}
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}
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}

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