source: class EcsJsonSerializerTest {
  
      @Test
      void serializeExceptionAsString() throws IOException {
  
target:         Exception exception = new Exception("foo");
          StringBuilder jsonBuilder = new StringBuilder();
          jsonBuilder.append('{');
          EcsJsonSerializer.serializeException(jsonBuilder, exception, false);
          jsonBuilder.append('}');
          JsonNode jsonNode = new ObjectMapper().readTree(jsonBuilder.toString());
  
          assertThat(jsonNode.get("error.type").textValue()).isEqualTo(exception.getClass().getName());
          assertThat(jsonNode.get("error.message").textValue()).isEqualTo("foo");
          StringWriter stringWriter = new StringWriter();
          exception.printStackTrace(new PrintWriter(stringWriter));
          assertThat(jsonNode.get("error.stack_trace").textValue()).isEqualTo(stringWriter.toString());
      }
  
  }