use unique name for backing index of unique constraints (#555)

* use unique name for backing index of unique constraints


* There may be edge cases where the index name could be null, so in this case we still using the table name + random identifier.

---------

Co-authored-by: filipe <flautert@liquibase.org>

src/main/java/liquibase/ext/hibernate/snapshot/UniqueConstraintSnapshotGenerator.java

@@ -117,7 +117,11 @@ protected Index getBackingIndex(UniqueConstraint uniqueConstraint, org.hibernate
         index.setRelation(uniqueConstraint.getRelation());
         index.setColumns(uniqueConstraint.getColumns());
         index.setUnique(true);
-        index.setName(String.format("%s_%s_IX",hibernateTable.getName(), StringUtil.randomIdentifer(4)));
+        if (StringUtil.isNotEmpty(uniqueConstraint.getName())) {
+            index.setName(uniqueConstraint.getName() + "_IX");
+        } else {
+            index.setName(String.format("%s_%s_IX",hibernateTable.getName(), StringUtil.randomIdentifer(4)));
+        }
 
         return index;
     }

src/test/java/com/example/ejb3/auction/Item.java

@@ -12,6 +12,9 @@ public class Item {
     @Column(unique = true)
     private String name;
 
+    @Column(unique = true)
+    private String key;
+
     public long getId() {
         return id;
     }
@@ -28,4 +31,7 @@ public void setName(String name) {
         this.name = name;
     }
 
+    public String getKey() { return key; }
+
+    public void setKey(String key) { this.key = key; }
 }

src/test/java/liquibase/ext/hibernate/SpringPackageScanningIntegrationTest.java

@@ -124,6 +124,7 @@ public void runGeneratedChangeLog() throws Exception {
 
         assertEquals(differences, 0, diffResult.getMissingObjects().size());
         assertEquals(differences, 0, diffResult.getUnexpectedObjects().size());
+        assertEquals(differences, 0, diffResult.getChangedObjects(UniqueConstraint.class).size());
 //        assertEquals(differences, 0, diffResult.getChangedObjects().size()); //unimportant differences in schema name and datatypes causing test to fail
 
     }