Register model converters only if they are not registered already - f…

…ixes #647 #648

springdoc-openapi-common/src/main/java/org/springdoc/core/converters/ModelConverterRegistrar.java

@@ -20,51 +20,54 @@
 
 package org.springdoc.core.converters;
 
-import io.swagger.v3.core.converter.ModelConverter;
-import io.swagger.v3.core.converter.ModelConverters;
-
 import java.lang.reflect.Field;
 import java.util.List;
 import java.util.Optional;
 
+import io.swagger.v3.core.converter.ModelConverter;
+import io.swagger.v3.core.converter.ModelConverters;
+import org.apache.commons.lang3.reflect.FieldUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  * Wrapper for model converters to only register converters once
  */
 public class ModelConverterRegistrar {
 
+	private static final ModelConverters modelConvertersInstance = ModelConverters.getInstance();
+	private static final Logger LOGGER = LoggerFactory.getLogger(ModelConverterRegistrar.class);
+
 	/**
 	 * @param modelConverters spring registered model converter beans which have to be
 	 *                        registered in {@link ModelConverters} instance
 	 */
 	public ModelConverterRegistrar(List<ModelConverter> modelConverters) {
 		for (ModelConverter modelConverter : modelConverters) {
 			Optional<ModelConverter> registeredConverterOptional = getRegisteredConverterSameAs(modelConverter);
-
-			ModelConverters modelConvertersInstance = ModelConverters.getInstance();
 			registeredConverterOptional.ifPresent(modelConvertersInstance::removeConverter);
 			modelConvertersInstance.addConverter(modelConverter);
 		}
 	}
 
 	private Optional<ModelConverter> getRegisteredConverterSameAs(ModelConverter modelConverter) {
 		try {
-			Field convertersField = ModelConverters.class.getDeclaredField("converters");
-			ModelConverters modelConvertersInstance = ModelConverters.getInstance();
-			convertersField.setAccessible(true);
+			Field convertersField = FieldUtils.getDeclaredField(ModelConverters.class, "converters", true);
 			List<ModelConverter> modelConverters = (List<ModelConverter>) convertersField.get(modelConvertersInstance);
 			return modelConverters.stream()
 					.filter(registeredModelConverter -> isSameConverter(registeredModelConverter, modelConverter))
 					.findFirst();
-		} catch (NoSuchFieldException | IllegalAccessException exception) {
+		}
+		catch (IllegalAccessException exception) {
+			LOGGER.error(exception.getMessage(), exception);
 			throw new RuntimeException(exception);
 		}
 	}
 
 	private boolean isSameConverter(ModelConverter modelConverter1, ModelConverter modelConverter2) {
-		// for now we are comparing using the converter types which may not be what we want
+		// comparing by the converter type
 		Class<? extends ModelConverter> modelConverter1Class = modelConverter1.getClass();
 		Class<? extends ModelConverter> modelConverter2Class = modelConverter2.getClass();
-
 		return modelConverter1Class.equals(modelConverter2Class);
 	}
 }