HHH-11101 - Missing unique constraint for many-to-many with unique=true in list mapping

(cherry picked from commit 9cf4fecbfe)

hibernate-core/src/main/java/org/hibernate/boot/model/source/internal/hbm/PluralAttributeElementSourceBasicImpl.java

@@ -71,6 +71,11 @@ public class PluralAttributeElementSourceBasicImpl
 						return !jaxbElement.isNotNull();
 					}
 
+					@Override
+					public boolean isUnique() {
+						return jaxbElement.isUnique();
+					}
+
 					@Override
 					public SizeSource getSizeSource() {
 						return Helper.interpretSizeSource(

hibernate-core/src/main/java/org/hibernate/boot/model/source/internal/hbm/PluralAttributeElementSourceManyToManyImpl.java

@@ -66,6 +66,11 @@ public class PluralAttributeElementSourceManyToManyImpl
 						return null;
 					}
 
+					@Override
+					public boolean isUnique() {
+						return jaxbManyToManyElement.isUnique();
+					}
+
 					@Override
 					public String getFormulaAttribute() {
 						return jaxbManyToManyElement.getFormulaAttribute();