Protected getContentType in DecoderHttpMessageReader

Issue: SPR-16856

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

@@ -93,7 +93,15 @@ public class DecoderHttpMessageReader<T> implements HttpMessageReader<T> {
 		return this.decoder.decodeToMono(message.getBody(), elementType, contentType, hints);
 	}
 
-	private MediaType getContentType(HttpMessage inputMessage) {
+	/**
+	 * Determine the Content-Type of the HTTP message based on the
+	 * "Content-Type" header or otherwise default to
+	 * {@link MediaType#APPLICATION_OCTET_STREAM}.
+	 * @param inputMessage the HTTP message
+	 * @return the MediaType, possibly {@code null}.
+	 */
+	@Nullable
+	protected MediaType getContentType(HttpMessage inputMessage) {
 		MediaType contentType = inputMessage.getHeaders().getContentType();
 		return (contentType != null ? contentType : MediaType.APPLICATION_OCTET_STREAM);
 	}

spring-web/src/main/java/org/springframework/web/client/HttpMessageConverterExtractor.java

@@ -120,6 +120,13 @@ public class HttpMessageConverterExtractor<T> implements ResponseExtractor<T> {
 				"for response type [" + this.responseType + "] and content type [" + contentType + "]");
 	}
 
+	/**
+	 * Determine the Content-Type of the response based on the "Content-Type"
+	 * header or otherwise default to {@link MediaType#APPLICATION_OCTET_STREAM}.
+	 * @param response the response
+	 * @return the MediaType, possibly {@code null}.
+	 */
+	@Nullable
 	protected MediaType getContentType(ClientHttpResponse response) {
 		MediaType contentType = response.getHeaders().getContentType();
 		if (contentType == null) {