Replaced null with () -> null for the fallback value

Author: vaisakhkannan

src/main/java/io/openliberty/tools/intellij/lsp4mp4ij/psi/core/java/validators/annotations/AnnotationValidator.java

@@ -96,7 +96,7 @@ public String validate(String value, AnnotationAttributeRule rule) {
 					}
 					return rule.validate(value);
 				},
-				null,  // Fallback value in case of exception
+				() -> null,  // Fallback value supplier in case of exception
 				e -> LOGGER.log(Level.WARNING, e.getLocalizedMessage(), e)
 		);
 	}

src/main/java/io/openliberty/tools/intellij/lsp4mp4ij/psi/internal/core/java/corrections/JavaDiagnosticsDefinition.java

@@ -65,7 +65,7 @@ public void beginDiagnostics(JavaDiagnosticsContext context) {
                 getInstance().beginDiagnostics(context);
                 return true;
             },
-                null,
+            () -> null,  // Fallback value supplier in case of exception
             e -> LOGGER.log(Level.WARNING, "Error while calling beginDiagnostics", e)
         );
     }
@@ -90,7 +90,7 @@ public void endDiagnostics(JavaDiagnosticsContext context) {
                 getInstance().endDiagnostics(context);
                 return true;
             },
-                null,
+            () -> null,  // Fallback value supplier in case of exception
             e -> LOGGER.log(Level.WARNING, "Error while calling endDiagnostics", e)
         );
     }

src/main/java/io/openliberty/tools/intellij/util/ExceptionUtil.java

@@ -46,7 +46,7 @@ public static void executeWithWorkspaceEditHandling(JavaCodeActionResolveContext
                 toResolve.setEdit(we);
                 return true;
             },
-                null,
+            () -> null,  // Fallback value supplier in case of exception
             e -> logger.log(Level.WARNING, logMessage, e)
         );
     }