[HttpProblem] common validation shorthands

docs/asciidoc/problem-details.adoc

@@ -57,6 +57,13 @@ Don't overuse it, the problem should have meaningful `title` and `detail` when p
 - `HttpProblem.valueOf(StatusCode status, String title)` - with custom `title`
 - `HttpProblem.valueOf(StatusCode status, String title, String detail)` - with `title` and `detail`
 
+and couple shorthands for the most common validation codes:
+
+- `HttpProblem.badRequest(String title, String detail)` - for _400 Bad Request_
+- `HttpProblem.notFound(String title, String detail)` - for _404 Not Found_
+- `HttpProblem.unprocessableEntity(String title, String detail)` - for _422 Unprocessable Entity_
+- `HttpProblem.internalServerError()` - for _500 Internal Server Error_
+
 `HttpProblem` extends `RuntimeException` so you can naturally throw it (as you do with exceptions):
 
 .Java

jooby/src/main/java/io/jooby/problem/HttpProblem.java

@@ -67,6 +67,54 @@ public static HttpProblem valueOf(StatusCode status) {
     return builder().title(status.reason()).status(status).build();
   }
 
+  public static HttpProblem badRequest(String title, String detail) {
+    return builder()
+        .title(title)
+        .status(StatusCode.BAD_REQUEST)
+        .detail(detail)
+        .build();
+  }
+
+  public static HttpProblem badRequest(String detail) {
+    return builder()
+        .title(StatusCode.BAD_REQUEST.reason())
+        .status(StatusCode.BAD_REQUEST)
+        .detail(detail)
+        .build();
+  }
+
+  public static HttpProblem notFound(String title, String detail) {
+    return builder()
+        .title(title)
+        .status(StatusCode.NOT_FOUND)
+        .detail(detail)
+        .build();
+  }
+
+  public static HttpProblem notFound(String detail) {
+    return builder()
+        .title(StatusCode.NOT_FOUND.reason())
+        .status(StatusCode.NOT_FOUND)
+        .detail(detail)
+        .build();
+  }
+
+  public static HttpProblem unprocessableEntity(String title, String detail) {
+    return builder()
+        .title(title)
+        .status(StatusCode.UNPROCESSABLE_ENTITY)
+        .detail(detail)
+        .build();
+  }
+
+  public static HttpProblem unprocessableEntity(String detail) {
+    return builder()
+        .title(StatusCode.UNPROCESSABLE_ENTITY.reason())
+        .status(StatusCode.UNPROCESSABLE_ENTITY)
+        .detail(detail)
+        .build();
+  }
+
   public static HttpProblem internalServerError() {
     return builder()
         .title(INTERNAL_ERROR_TITLE)