IS NOT NULL failed in Elasticsearch Adapter

@Test void testIsNotNull() {
    CalciteAssert.that()
        .with(newConnectionFactory())
        // "where num is not null" also failed
        .query("select * from view where num > 42 or num < 42 or num = 42")
        .returns("");
  }

PredicateAnalyzer$PredicateAnalyzerException: Unsupported expression: [org.apache.calcite.adapter.elasticsearch.PredicateAnalyzer$CastExpression@26545ea]