HHH-18621 attempt to not dupe identity column clause when using @column(columnDefinition)

This is just a best effort, not robust at all

Author: gavinking

hibernate-core/src/main/java/org/hibernate/tool/schema/internal/ColumnDefinitions.java

@@ -197,7 +197,11 @@ private static void appendColumnDefinition(
 			}
 			final String identityColumnString = dialect.getIdentityColumnSupport()
 					.getIdentityColumnString( column.getSqlTypeCode( metadata ) );
-			definition.append( ' ' ).append( identityColumnString );
+			// the custom columnDefinition might have already included the
+			// identity column generation clause, so try not to add it twice
+			if ( !definition.toString().toLowerCase(Locale.ROOT).contains( identityColumnString ) ) {
+				definition.append( ' ' ).append( identityColumnString );
+			}
 		}
 		else {
 			final String columnType = column.getSqlType( metadata );