PackageDescr packageDescr = DescrFactory.newPackage().name("examples.drools")
                .newImport().target("java.math.BigDecimal").end()
                .newAccumulateImport().target("examples.drools.accumulate.OriginalFunction").functionName("originalFunction").end()
                .newRule().name("Test Rule")
                    .lhs()
                        .accumulate()
                            .source().pattern().type("TargetFact").id("$target", false)
                            .end()
                        .end()
                    .function("originalFunction", "$accumulateResult", false, "$target.hoge")
                    .constraint("true")
                    .end()
                .end()
                .rhs("System.out.println($accumulateResult);")
                .end()
            .end().getDescr();

        String drl = new DrlDumper().dump(packageDescr);