Start of usage exception

Author: jknack

jooby/src/main/java/io/jooby/Jooby.java

@@ -283,9 +283,7 @@ public <T> Jooby mvc(@Nonnull Class<T> router, @Nonnull Provider<T> provider) {
       MvcFactory module = stream(modules.spliterator(), false)
           .filter(it -> it.supports(router))
           .findFirst()
-          // TODO: Usage exception
-          .orElseThrow(() -> new IllegalStateException("Mvc module not found: " + router.getName()
-              + ". Make sure annotation processor is configured properly."));
+          .orElseThrow(() -> Usage.mvcRouteMissing(router));
       Extension extension = module.create(provider);
       extension.install(this);
       return this;

jooby/src/main/java/io/jooby/Usage.java

@@ -0,0 +1,31 @@
+package io.jooby;
+
+import javax.annotation.Nonnull;
+
+/**
+ * Usage exceptions. They provide a descriptive message with a link for a detailed section.
+ *
+ * @since 2.1.0
+ */
+public class Usage extends RuntimeException {
+  /**
+   * Creates a new Usage exception.
+   *
+   * @param message Message.
+   * @param id Link to detailed section.
+   */
+  public Usage(@Nonnull String message, @Nonnull String id) {
+    super((message + "\nFor more details, please visit: https://io.jooby/usage#" + id));
+  }
+
+  /**
+   * Creates a mvc route missing exception.
+   *
+   * @param mvcRoute Mvc route.
+   * @return Usage exception.
+   */
+  public static @Nonnull Usage mvcRouteMissing(@Nonnull Class mvcRoute) {
+    return new Usage("Mvc route not found: `" + mvcRoute.getName()
+        + "`. Make sure Jooby annotation processor is configured properly.", "mvc-route-apt");
+  }
+}