Elasticsearch query from Java REST High level client returns different/undesirable results compared to execution of Query DSL on Kibana

Question

I'm implementing an elasticsearch search feature using Java High-level REST client, which queries the ES index residing on one of the clusters hosted on the cloud. My intended query JSON DSL looks like this,

{
  "query" :{
      "bool": {
        "should" :[
          {
            "query_string":{
              "query":"cla-180",
              "default_field": "product_title",
              "boost" : 3
            }
          },
          {
            "match" : {
              "product_title" : {
                "query" : "cla-180",
                 "fuzziness" : "AUTO"
              }
            }
          }
        ]
    }
  }
}

Corresponding to this, I have written the code to be executed using the Java High-level REST client, which performs the same functionality as the DSL above.

BoolQueryBuilder boolQueryBuilder = buildBoolQuery();
boolQueryBuilder.should(QueryBuilders.queryStringQuery("cla-180").defaultField("product_title")).boost(3);
boolQueryBuilder.should(QueryBuilders.matchQuery("product_title", "cla-180").fuzziness(Fuzziness.AUTO));

SearchSourceBuilder sourceBuilder = new SearchSourceBuilder();
sourceBuilder.query(boolQueryBuilder);

What I'm noticing is that the search results for the java methods are different to the results when I execute the DSL on kibana directly. I find records that have no relation to the search content that I have given above when executed from Java. I consider this weird because I guess I have implemented the Java code to match that of the JSON query DSL given above.

When I try to print the generated JSON from the Java side, its output is like this below,

{
    "query": {
    "bool" : {
    "should" : [
      {
        "query_string" : {
          "query" : "cla-180",
          "default_field" : "product_title",
          "fields" : [ ],
          "type" : "best_fields",
          "default_operator" : "or",
          "max_determinized_states" : 10000,
          "enable_position_increments" : true,
          "fuzziness" : "AUTO",
          "fuzzy_prefix_length" : 0,
          "fuzzy_max_expansions" : 50,
          "phrase_slop" : 0,
          "escape" : false,
          "auto_generate_synonyms_phrase_query" : true,
          "fuzzy_transpositions" : true,
          "boost" : 1.0
        }
      },
      {
        "match" : {
          "product_title" : {
            "query" : "cla-180",
            "operator" : "OR",
            "fuzziness" : "AUTO",
            "prefix_length" : 0,
            "max_expansions" : 50,
            "fuzzy_transpositions" : true,
            "lenient" : false,
            "zero_terms_query" : "NONE",
            "auto_generate_synonyms_phrase_query" : true,
            "boost" : 1.0
          }
        }
      }
    ],
    "adjust_pure_negative" : true,
    "minimum_should_match" : "1",
    "boost" : 3.0
  }
    }
}

Am I missing something in my java code, that makes the search results to be returned in an undesirable fashion? Or what could be the reason for this mismatch in records that are being returned in these 2 methods?

Thanks in advance!