DATAJPA-1575 - Conditionally register SurroundingTransactionDetectorMethodInterceptor.

We now register SurroundingTransactionDetectorMethodInterceptor only for interfaces that return a Stream to detect a surrounding transaction.

src/main/java/org/springframework/data/jpa/repository/support/JpaRepositoryFactory.java

@@ -20,7 +20,9 @@ import static org.springframework.data.querydsl.QuerydslUtils.*;
 import lombok.extern.slf4j.Slf4j;
 
 import java.io.Serializable;
+import java.lang.reflect.Method;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 import javax.persistence.EntityManager;
 import javax.persistence.Tuple;
@@ -46,12 +48,14 @@ import org.springframework.data.repository.core.support.QueryCreationListener;
 import org.springframework.data.repository.core.support.RepositoryComposition;
 import org.springframework.data.repository.core.support.RepositoryFactorySupport;
 import org.springframework.data.repository.core.support.RepositoryFragment;
+import org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor;
 import org.springframework.data.repository.query.QueryLookupStrategy;
 import org.springframework.data.repository.query.QueryLookupStrategy.Key;
 import org.springframework.data.repository.query.QueryMethodEvaluationContextProvider;
 import org.springframework.data.repository.query.ReturnedType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
+import org.springframework.util.ReflectionUtils;
 
 /**
  * JPA specific generic repository factory.
@@ -86,6 +90,12 @@ public class JpaRepositoryFactory extends RepositoryFactorySupport {
 		this.entityPathResolver = SimpleEntityPathResolver.INSTANCE;
 
 		addRepositoryProxyPostProcessor(crudMethodMetadataPostProcessor);
+		addRepositoryProxyPostProcessor((factory, repositoryInformation) -> {
+
+			if (hasMethodReturningStream(repositoryInformation.getRepositoryInterface())) {
+				factory.addAdvice(SurroundingTransactionDetectorMethodInterceptor.INSTANCE);
+			}
+		});
 
 		if (extractor.equals(PersistenceProvider.ECLIPSELINK)) {
 			addQueryCreationListener(new EclipseLinkProjectionQueryCreationListener(entityManager));
@@ -231,6 +241,19 @@ public class JpaRepositoryFactory extends RepositoryFactorySupport {
 		return fragments;
 	}
 
+	private static boolean hasMethodReturningStream(Class<?> repositoryClass) {
+
+		Method[] methods = ReflectionUtils.getAllDeclaredMethods(repositoryClass);
+
+		for (Method method : methods) {
+			if (Stream.class.isAssignableFrom(method.getReturnType())) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
 	/**
 	 * Query creation listener that informs EclipseLink users that they have to be extra careful when defining repository
 	 * query methods using projections as we have to rely on the declaration order of the accessors in projection