不支持使用负号“-”

[starShinning]

@Test
public void qlBigDecimalTest() throws Exception {

    ExpressRunner runner = new ExpressRunner(true, false);
    runner.setShortCircuit(true);
    DefaultContext context = new DefaultContext();
    BigDecimal value = new BigDecimal("12.22");
    context.put("b", value);
    Object execute = runner.execute("-b", context, null, false, false);
    System.out.println(execute);
}

com.ql.util.express.exception.QLCompileException: 程序错误，不满足语法规范，没有匹配到合适的语法,最大匹配致[0:-1]

at com.ql.util.express.match.QLPattern.findMatchStatement(QLPattern.java:30)
at com.ql.util.express.parse.ExpressParse.parse(ExpressParse.java:404)
at com.ql.util.express.parse.ExpressParse.parse(ExpressParse.java:362)
at com.ql.util.express.parse.ExpressParse.parse(ExpressParse.java:335)
at com.ql.util.express.ExpressRunner.parseInstructionSet(ExpressRunner.java:678)
at com.ql.util.express.ExpressRunner.executeInner(ExpressRunner.java:638)
at com.ql.util.express.ExpressRunner.execute(ExpressRunner.java:629)
at com.example.demo.ExpressTest.qlBigDecimalTest(ExpressTest.java:74)

使用过程中想直接转为负数，但是报错。
这个有什么方法能处理吗，还是只能写成 "0-b"