import org.apache.solr.client.solrj.SolrQuery;

public class Test {
    public static void main(String[] args) {
        SolrQuery solrQuery = new SolrQuery();
        System.out.println(JSONObject.toJSONString(solrQuery, SerializerFeature.DisableCircularReferenceDetect, SerializerFeature.WriteNullBooleanAsFalse));
    }
}

Exception in thread "main" java.lang.StackOverflowError
	at org.apache.solr.common.params.ModifiableSolrParams.getParameterNames(ModifiableSolrParams.java:202)
	at org.apache.solr.client.solrj.SolrQuery.getCopy(SolrQuery.java:1181)
	at com.alibaba.fastjson.serializer.ASMSerializer_1_SolrQuery.writeDirectNonContext(Unknown Source)
	at com.alibaba.fastjson.serializer.ASMSerializer_1_SolrQuery.writeDirectNonContext(Unknown Source)

1、fastjson 最新版本，1.2.51(测试了多个版本)
2、Solr 7.5.0(测试了多个版本)

测试发现使用Gson正常序列化

java版本：1.8，1.7都测试过
机器：linux,mac 都有出现

@wenshao