Remove a compilation warning (#6294)

Author: nadment

core/src/main/java/org/apache/hop/core/gui/plugin/action/GuiActionLambdaBuilder.java

@@ -67,7 +67,7 @@ public GuiAction createLambda(GuiAction guiAction, T methodParameter, IGuiRefres
 
       try {
         Method getInstanceMethod = guiPluginClass.getDeclaredMethod("getInstance");
-        guiPlugin = getInstanceMethod.invoke(null, null);
+        guiPlugin = getInstanceMethod.invoke(null, (Object[]) null);
       } catch (Exception nsme) {
         // On the rebound we'll try to simply construct a new instance...
         // This makes the plugins even simpler.

ui/src/main/java/org/apache/hop/ui/hopgui/context/BaseGuiContextHandler.java

@@ -124,7 +124,7 @@ public Object getFilterObject(GuiActionFilter actionFilter) throws HopException
       Object guiPlugin;
       try {
         Method getInstanceMethod = filterClass.getDeclaredMethod("getInstance");
-        guiPlugin = getInstanceMethod.invoke(null, null);
+        guiPlugin = getInstanceMethod.invoke(null, (Object[]) null);
       } catch (Exception nsme) {
         // On the rebound we'll try to simply construct a new instance...
         // This makes the plugins even simpler.

ui/src/test/java/org/apache/hop/ui/core/bus/HopGuiEventsHandlerTest.java

@@ -100,7 +100,8 @@ public void testAddEventExceptions() {
     // We need at least 1 non-null event ID
     //
     assertThrows(RuntimeException.class, () -> events.addEventListener("guiId-1", e -> {}));
-    assertThrows(RuntimeException.class, () -> events.addEventListener("guiId-1", e -> {}, null));
+    assertThrows(
+        RuntimeException.class, () -> events.addEventListener("guiId-1", e -> {}, (String[]) null));
     assertThrows(RuntimeException.class, () -> events.addEventListener("guiId-1", e -> {}, ""));
   }
 
@@ -110,7 +111,7 @@ public void testFireEventExceptions() {
     //
     assertThrows(RuntimeException.class, () -> events.fire());
     assertThrows(RuntimeException.class, () -> events.fire(""));
-    assertThrows(RuntimeException.class, () -> events.fire(null));
+    assertThrows(RuntimeException.class, () -> events.fire((Object[]) null));
   }
 
   @Test