Note on 'generateDdl' versus JPA 2.1 schema generation

Issue: SPR-13040

spring-orm/src/main/java/org/springframework/orm/jpa/vendor/AbstractJpaVendorAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2015 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -78,6 +78,10 @@ public abstract class AbstractJpaVendorAdapter implements JpaVendorAdapter {
 	 * <p>Note that the exact semantics of this flag depend on the underlying
 	 * persistence provider. For any more advanced needs, specify the appropriate
 	 * vendor-specific settings as "jpaProperties".
+	 * <p><b>NOTE: Do not set this flag to 'true' while also setting JPA 2.1's
+	 * {@code javax.persistence.schema-generation.database.action} property.</b>
+	 * These two schema generation mechanisms - standard JPA versus provider-native -
+	 * are mutually exclusive, e.g. with Hibernate 5.
 	 * @see org.springframework.orm.jpa.AbstractEntityManagerFactoryBean#setJpaProperties
 	 */
 	public void setGenerateDdl(boolean generateDdl) {