Allow any Accept and Content-Type raw values

See gh-2079

spring-test/src/main/java/org/springframework/test/web/servlet/request/MockHttpServletRequestBuilder.java

@@ -294,7 +294,8 @@ public class MockHttpServletRequestBuilder
 	 * @since 4.1.2
 	 */
 	public MockHttpServletRequestBuilder contentType(String contentType) {
-		this.contentType = MediaType.parseMediaType(contentType).toString();
+		Assert.notNull(contentType, "'contentType' must not be null");
+		this.contentType = contentType;
 		return this;
 	}
 
@@ -314,11 +315,9 @@ public class MockHttpServletRequestBuilder
 	 */
 	public MockHttpServletRequestBuilder accept(String... mediaTypes) {
 		Assert.notEmpty(mediaTypes, "'mediaTypes' must not be empty");
-		List<MediaType> result = new ArrayList<>(mediaTypes.length);
-		for (String mediaType : mediaTypes) {
-			result.add(MediaType.parseMediaType(mediaType));
-		}
-		this.headers.set("Accept", MediaType.toString(result));
+		List<String> result = new ArrayList<>(mediaTypes.length);
+		result.addAll(Arrays.asList(mediaTypes));
+		this.headers.set("Accept", String.join(", ", result));
 		return this;
 	}
 
@@ -712,7 +711,7 @@ public class MockHttpServletRequestBuilder
 
 		if (this.content != null && this.content.length > 0) {
 			String requestContentType = request.getContentType();
-			if (requestContentType != null) {
+			if (requestContentType != null && isValidContentType(requestContentType)) {
 				MediaType mediaType = MediaType.parseMediaType(requestContentType);
 				if (MediaType.APPLICATION_FORM_URLENCODED.includes(mediaType)) {
 					addRequestParams(request, parseFormData(mediaType));
@@ -742,6 +741,26 @@ public class MockHttpServletRequestBuilder
 		return request;
 	}
 
+	/**
+	 * Some validation checks to find out if processing of a string value make sense.
+	 */
+	private boolean isValidContentType(String mimeType) {
+		if (!StringUtils.hasLength(mimeType)) {
+			return false;
+		}
+
+		int index = mimeType.indexOf(';');
+		String fullType = (index >= 0 ? mimeType.substring(0, index) : mimeType).trim();
+		if (fullType.isEmpty()) {
+			return false;
+		}
+		int subIndex = fullType.indexOf('/');
+		if (subIndex == -1) {
+			return false;
+		}
+		return subIndex != fullType.length() - 1;
+	}
+
 	/**
 	 * Create a new {@link MockHttpServletRequest} based on the supplied
 	 * {@code ServletContext}.