Register custom before default codecs

Closes gh-22612

spring-web/src/main/java/org/springframework/http/codec/support/BaseCodecConfigurer.java

 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -72,11 +72,11 @@ class BaseCodecConfigurer implements CodecConfigurer {
 	public List<HttpMessageReader<?>> getReaders() {
 		List<HttpMessageReader<?>> result = new ArrayList<>();
 
-		result.addAll(this.defaultCodecs.getTypedReaders());
 		result.addAll(this.customCodecs.getTypedReaders());
+		result.addAll(this.defaultCodecs.getTypedReaders());
 
-		result.addAll(this.defaultCodecs.getObjectReaders());
 		result.addAll(this.customCodecs.getObjectReaders());
+		result.addAll(this.defaultCodecs.getObjectReaders());
 
 		result.addAll(this.defaultCodecs.getCatchAllReaders());
 		return result;
@@ -96,11 +96,11 @@ class BaseCodecConfigurer implements CodecConfigurer {
 	protected List<HttpMessageWriter<?>> getWritersInternal(boolean forMultipart) {
 		List<HttpMessageWriter<?>> result = new ArrayList<>();
 
-		result.addAll(this.defaultCodecs.getTypedWriters(forMultipart));
 		result.addAll(this.customCodecs.getTypedWriters());
+		result.addAll(this.defaultCodecs.getTypedWriters(forMultipart));
 
-		result.addAll(this.defaultCodecs.getObjectWriters(forMultipart));
 		result.addAll(this.customCodecs.getObjectWriters());
+		result.addAll(this.defaultCodecs.getObjectWriters(forMultipart));
 
 		result.addAll(this.defaultCodecs.getCatchAllWriters());
 		return result;

spring-web/src/test/java/org/springframework/http/codec/support/CodecConfigurerTests.java

@@ -125,6 +125,8 @@ public class CodecConfigurerTests {
 		List<HttpMessageReader<?>> readers = this.configurer.getReaders();
 
 		assertEquals(15, readers.size());
+		assertSame(customDecoder1, getNextDecoder(readers));
+		assertSame(customReader1, readers.get(this.index.getAndIncrement()));
 		assertEquals(ByteArrayDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(ByteBufferDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(DataBufferDecoder.class, getNextDecoder(readers).getClass());
@@ -132,13 +134,11 @@ public class CodecConfigurerTests {
 		assertEquals(StringDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(ProtobufDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(FormHttpMessageReader.class, readers.get(this.index.getAndIncrement()).getClass());
-		assertSame(customDecoder1, getNextDecoder(readers));
-		assertSame(customReader1, readers.get(this.index.getAndIncrement()));
+		assertSame(customDecoder2, getNextDecoder(readers));
+		assertSame(customReader2, readers.get(this.index.getAndIncrement()));
 		assertEquals(Jackson2JsonDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(Jackson2SmileDecoder.class, getNextDecoder(readers).getClass());
 		assertEquals(Jaxb2XmlDecoder.class, getNextDecoder(readers).getClass());
-		assertSame(customDecoder2, getNextDecoder(readers));
-		assertSame(customReader2, readers.get(this.index.getAndIncrement()));
 		assertEquals(StringDecoder.class, getNextDecoder(readers).getClass());
 	}
 
@@ -165,19 +165,19 @@ public class CodecConfigurerTests {
 		List<HttpMessageWriter<?>> writers = this.configurer.getWriters();
 
 		assertEquals(14, writers.size());
+		assertSame(customEncoder1, getNextEncoder(writers));
+		assertSame(customWriter1, writers.get(this.index.getAndIncrement()));
 		assertEquals(ByteArrayEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(ByteBufferEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(DataBufferEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(ResourceHttpMessageWriter.class, writers.get(index.getAndIncrement()).getClass());
 		assertEquals(CharSequenceEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(ProtobufHttpMessageWriter.class, writers.get(index.getAndIncrement()).getClass());
-		assertSame(customEncoder1, getNextEncoder(writers));
-		assertSame(customWriter1, writers.get(this.index.getAndIncrement()));
+		assertSame(customEncoder2, getNextEncoder(writers));
+		assertSame(customWriter2, writers.get(this.index.getAndIncrement()));
 		assertEquals(Jackson2JsonEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(Jackson2SmileEncoder.class, getNextEncoder(writers).getClass());
 		assertEquals(Jaxb2XmlEncoder.class, getNextEncoder(writers).getClass());
-		assertSame(customEncoder2, getNextEncoder(writers));
-		assertSame(customWriter2, writers.get(this.index.getAndIncrement()));
 		assertEquals(CharSequenceEncoder.class, getNextEncoder(writers).getClass());
 	}