q
.SpanWithin(sn => sn
    .Name("named_query")
    .Boost(1.1)
    .Little(i=>i
        .SpanTerm(st=>st.Field("field1").Value("hoya"))
    )
    .Big(e=>e
        .SpanTerm(st=>st.Field("field1").Value("hoya2"))
    )
)

new SpanWithinQuery
{
    Name = "named_query",
    Boost = 1.1,
    Little = new SpanQuery { SpanTerm = new SpanTermQuery { Field = "field1", Value = "hoya"} },
    Big = new SpanQuery { SpanTerm = new SpanTermQuery { Field = "field1", Value = "hoya2"} },
}

{
  "span_within": {
    "_name": "named_query",
    "boost": 1.1,
    "little": {
      "span_term": {
        "field1": {
          "value": "hoya"
        }
      }
    },
    "big": {
      "span_term": {
        "field1": {
          "value": "hoya2"
        }
      }
    }
  }
}