FailedFuture should always have a cause even when the provided cause …

…is null - fixes #1910

src/main/java/io/vertx/core/impl/FailedFuture.java

@@ -26,10 +26,18 @@ public class FailedFuture<T> implements Future<T> {
 
   private final Throwable cause;
 
-  FailedFuture(Throwable cause) {
-    this.cause = cause;
-  }
-
+  /**
+   * Create a future that has already failed
+   * @param t the throwable
+   */
+  FailedFuture(Throwable t) {
+    cause = t != null ? t : new NoStackTraceThrowable(null);
+  }
+
+  /**
+   * Create a future that has already failed
+   * @param failureMessage the failure message
+   */
   FailedFuture(String failureMessage) {
     this(new NoStackTraceThrowable(failureMessage));
   }

src/main/java/io/vertx/core/impl/FutureImpl.java

@@ -33,30 +33,6 @@ class FutureImpl<T> implements Future<T>, Handler<AsyncResult<T>> {
   FutureImpl() {
   }
 
-  /**
-   * Create a future that has already failed
-   * @param t the throwable
-   */
-  FutureImpl(Throwable t) {
-    fail(t != null ? t : new NoStackTraceThrowable(null));
-  }
-
-  /**
-   * Create a future that has already failed
-   * @param failureMessage the failure message
-   */
-  FutureImpl(String failureMessage) {
-    this(new NoStackTraceThrowable(failureMessage));
-  }
-
-  /**
-   * Create a future that has already succeeded
-   * @param result the result
-   */
-  FutureImpl(T result) {
-    complete(result);
-  }
-
   /**
    * The result of the operation. This will be null if the operation failed.
    */

src/main/java/io/vertx/core/impl/SucceededFuture.java

@@ -26,6 +26,10 @@ class SucceededFuture<T> implements Future<T> {
 
   private final T result;
 
+  /**
+   * Create a future that has already succeeded
+   * @param result the result
+   */
   SucceededFuture(T result) {
     this.result = result;
   }