fix nullability customizer for polymorphic types

Author: SirCotare

src/main/java/it/aboutbits/springboot/toolbox/swagger/customization/default_not_null/NullableCustomizer.java

@@ -5,6 +5,7 @@
 import org.springdoc.core.customizers.OpenApiCustomizer;
 
 import java.util.ArrayList;
+import java.util.Map;
 
 public class NullableCustomizer implements OpenApiCustomizer {
     @Override
@@ -15,18 +16,32 @@ public void customise(OpenAPI openApi) {
         }
         openApi.getComponents().getSchemas().values()
                 .forEach(schema -> {
+                    var requiredProperties = new ArrayList<String>();
                     if (((Schema<?>) schema).getProperties() != null) {
-                        var requiredProperties = new ArrayList<String>();
-                        ((Schema<?>) schema).getProperties().forEach((propertyName, property) -> {
-                            if (property.getTitle() == null || !property.getTitle().equals("NULLABLE")) {
-                                requiredProperties.add(propertyName);
-                            }
-                            if (property.getTitle() != null && property.getTitle().equals("NULLABLE")) {
-                                property.setTitle(null);
+                        var properties = ((Schema<?>) schema).getProperties();
+                        processProperties(properties, requiredProperties);
+                    }
+                    if (schema.getAllOf() != null) {
+                        schema.getAllOf().forEach(allOfSchema -> {
+                            var allOfSchemaTyped = (Schema<?>) allOfSchema;
+                            if (allOfSchemaTyped.getProperties() != null) {
+                                var properties = allOfSchemaTyped.getProperties();
+                                processProperties(properties, requiredProperties);
                             }
                         });
-                        schema.setRequired(requiredProperties);
                     }
+                    schema.setRequired(requiredProperties);
                 });
     }
+
+    private static void processProperties(Map<String, Schema> properties, ArrayList<String> requiredProperties) {
+        properties.forEach((propertyName, property) -> {
+            if (property.getTitle() == null || !property.getTitle().equals("NULLABLE")) {
+                requiredProperties.add(propertyName);
+            }
+            if (property.getTitle() != null && property.getTitle().equals("NULLABLE")) {
+                property.setTitle(null);
+            }
+        });
+    }
 }