import com.squareup.moshi.JsonAdapter;
import com.squareup.moshi.Moshi;

//...


Employee[] employeeArray = employeeList.toArray(new Employee[employeeList.size()]);

Moshi moshi = new Moshi.Builder().build();

JsonAdapter<Employee[]> jsonAdapter = moshi.adapter(Employee[].class).indent("  ");
      
String json = jsonAdapter.toJson(employeeArray);