HHH-18367 Fix for Informix sum on case expression error

Author: VladoKuruc

hibernate-community-dialects/src/main/java/org/hibernate/community/dialect/InformixDialect.java

@@ -257,6 +257,7 @@ public void initializeFunctionRegistry(FunctionContributions functionContributio
 		super.initializeFunctionRegistry(functionContributions);
 
 		CommonFunctionFactory functionFactory = new CommonFunctionFactory(functionContributions);
+		functionFactory.aggregates( this, SqlAstNodeRenderingMode.NO_PLAIN_PARAMETER );
 		functionFactory.instr();
 		functionFactory.substr();
 		functionFactory.substringFromFor();