private void initRuleUnitClassName() {
        String ruleUnitClassName = rule.getRuleUnitClassName();
        boolean nameInferredFromResource = false;

        if ( ruleUnitClassName == null && rule.getResource() != null && rule.getResource().getSourcePath() != null ) {
            String drlPath = rule.getResource().getSourcePath();
            int lastSep = drlPath.lastIndexOf( '/' );
            if (lastSep >= 0) {
                drlPath = drlPath.substring( lastSep+1 );
            }
            ruleUnitClassName = rule.getPackage() + "." + drlPath.substring( 0, drlPath.lastIndexOf( '.' ) ).replace( '/', '.' );
            nameInferredFromResource = true;
        }

        if (ruleUnitClassName != null) {
            TypeResolver typeResolver = getPkg().getTypeResolver();
            boolean unitFound = false;
            Class<?> ruleUnitClass = ClassUtils.safeLoadClass(typeResolver.getClassLoader(), ruleUnitClassName);
            if (ruleUnitClass != null) {
                unitFound = RuleUnit.class.isAssignableFrom( ruleUnitClass );
                if ( unitFound && nameInferredFromResource ) {
                    rule.setRuleUnitClassName( ruleUnitClassName );
                }
            }

            if (!unitFound && !nameInferredFromResource) {
                addError( new RuleBuildError( rule, getParentDescr(), null,
                                              ruleUnitClassName + " is not a valid RuleUnit class name" ) );
            }
        }
    }