Fix incorrect Content-Type inference for POST/PUT/PATCH requests without body

Signed-off-by: banseok1216 <bansuk1216@naver.com>

Author: banseok1216

spring-restdocs-core/src/main/java/org/springframework/restdocs/http/HttpRequestSnippet.java

@@ -178,7 +178,7 @@ private void writeMultipartEnd(PrintWriter writer) {
 
 	private boolean requiresFormEncodingContentTypeHeader(OperationRequest request) {
 		return request.getHeaders().get(HttpHeaders.CONTENT_TYPE) == null && isPutPostOrPatch(request)
-				&& !includeParametersInUri(request);
+				&& request.getContent().length > 0 && !includeParametersInUri(request);
 	}
 
 	private Map<String, String> header(String name, String value) {
@@ -188,4 +188,4 @@ private Map<String, String> header(String name, String value) {
 		return header;
 	}
 
-}
+}

spring-restdocs-core/src/test/java/org/springframework/restdocs/http/HttpRequestSnippetTests.java

@@ -244,6 +244,22 @@ void deleteWithQueryString(OperationBuilder operationBuilder, AssertableSnippets
 			.isHttpRequest((request) -> request.delete("/foo?a=alpha&b=bravo").header("Host", "localhost"));
 	}
 
+	@RenderedSnippetTest
+	void postFormUrlEncodedRequestIsDocumentedWhenContentTypeIsExplicit(OperationBuilder operationBuilder,
+			AssertableSnippets snippets) throws IOException {
+		String body = "a=alpha&b=bravo";
+		new HttpRequestSnippet().document(operationBuilder.request("http://localhost/foo")
+			.method("POST")
+			.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+			.content(body)
+			.build());
+		assertThat(snippets.httpRequest()).isHttpRequest((request) -> request.post("/foo")
+			.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_FORM_URLENCODED_VALUE)
+			.header(HttpHeaders.HOST, "localhost")
+			.header(HttpHeaders.CONTENT_LENGTH, body.getBytes().length)
+			.content(body));
+	}
+
 	private String createPart(String content) {
 		return this.createPart(content, true);
 	}