Don't load resource bundles during annotation processing (fixes #1876)

picocli-codegen/src/main/java/picocli/codegen/annotation/processing/AbstractCommandSpecProcessor.java

@@ -4,6 +4,7 @@
 import picocli.CommandLine.Command;
 import picocli.CommandLine.IFactory;
 import picocli.CommandLine.Mixin;
+import picocli.CommandLine.Model;
 import picocli.CommandLine.Model.ArgGroupSpec;
 import picocli.CommandLine.Model.CommandSpec;
 import picocli.CommandLine.Model.IAnnotatedElement;
@@ -179,7 +180,7 @@ private static String stacktrace(Exception e) {
     }
 
     private boolean tryProcess(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
-
+        Model.Messages.setLoadBundles(false);
         new AnnotationValidator(processingEnv).validateAnnotations(roundEnv);
 
         Context context = new Context();

src/main/java/picocli/CommandLine.java

@@ -11599,6 +11599,7 @@ public <T> T getExtension(Class<T> cls) {
          * @see CommandSpec#qualifiedName(String)
          * @since 3.6 */
         public static class Messages {
+            private static boolean loadBundles = true;
             private final CommandSpec spec;
             private final String bundleBaseName;
             private final ResourceBundle rb;
@@ -11620,7 +11621,19 @@ public Messages(CommandSpec spec, String baseName, ResourceBundle rb) {
                 }
             }
             private static ResourceBundle createBundle(String baseName) {
-                return ResourceBundle.getBundle(baseName);
+                if (loadBundles) {
+                    return ResourceBundle.getBundle(baseName);
+                } else {
+                    return new ResourceBundle() {
+                        @Override
+                        protected Object handleGetObject(String key) {
+                            return null;
+                        }
+                        @Override
+                        public Enumeration<String> getKeys() {
+                            return Collections.emptyEnumeration();                       }
+                    };
+                }
             }
             private static String extractName(ResourceBundle rb) {
                 try { // ResourceBundle.getBaseBundleName was introduced in Java 8
@@ -11648,6 +11661,18 @@ private static Set<String> keys(ResourceBundle rb) {
                 for (Enumeration<String> k = rb.getKeys(); k.hasMoreElements(); keys.add(k.nextElement()));
                 return keys;
             }
+
+            /**
+             * During annotation processing, resource bundles may not be available on the
+             * classpath and thereby cause failures. This method allows for disabling
+             * loading of resource bundles during annotation processing, preventing such
+             * errors. 
+             * @since 4.7.1
+             * @param loadBundles true if bundles should be loaded (default), false if bundles should not be loaded
+             */
+            public static final void setLoadBundles(boolean loadBundles) {
+            	Messages.loadBundles = loadBundles;
+            }
 
             /** Returns a copy of the specified Messages object with the CommandSpec replaced by the specified one.
              * @param spec the CommandSpec of the returned Messages