Empty return webapp when searching for ID in the Mongo DB database (spring MVC+Thymeleaf)

Question

Controller class where the ID search method is found:

package br.com.apisw.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;

import br.com.apisw.models.Planeta;
import br.com.apisw.repositories.PlanetaRepository;

@Controller
public class PlanetaController {

    // Spring faz a injeção do repositório automaticamente
    @Autowired
    private PlanetaRepository repository;

    @GetMapping("/planeta/cadastrar")
    public String cadastrar(Model model) {
        // cria o objeto planeta e envia pro html
        model.addAttribute("planeta", new Planeta());
        return "planeta/cadastrar";

    }

    @PostMapping("/planeta/salvar")
    // recebendo o objeto planeta enviado do formulário
    public String salvar(@ModelAttribute Planeta planeta) {
        System.out.println(planeta);
        repository.salvar(planeta);
        return "redirect:/";
    }

    // metodo listar planetas
    @GetMapping("/planeta/listar")
    public String listar(Model model) {
        List<Planeta> planeta = repository.obterTodosPlanetas();
        model.addAttribute("planeta", planeta);
        return "planeta/listar";
    }

    // metodo pesquisar por nome
    @GetMapping("/planeta/pesquisarnome")
    public String pesquisarNome() {
        return "planeta/pesquisarnome";
    }

    // metodo pesquisar
    @GetMapping("/planeta/pesquisar")
    public String pesquisar(@RequestParam("nome") String nome, Model model) {
        List<Planeta> planetas = repository.pesquisarPor(nome);
        model.addAttribute("planeta", planetas);
        return "planeta/pesquisarnome";
    }



    // metodo pesquisar por id
    @GetMapping("/planeta/pesquisarid")
    public String pesquisarId() {
        return "planeta/pesquisarid";
    }

    // metodo pesquisar
    @GetMapping("/planeta/pesquisaridplaneta")
    public String pesquisarIdPlaneta(@RequestParam("id") String id, Model model) {
        List<Planeta> planetas = repository.pesquisarPorId(id);
        model.addAttribute("planeta", planetas);
        return "planeta/pesquisarid";
    }

}

Repositories class where the searchPorId method brings the collections of planets in the mongoDB database:

package br.com.apisw.repositories;

import java.util.ArrayList;
import java.util.List;

import org.bson.Document;
import org.bson.codecs.Codec;
import org.bson.codecs.configuration.CodecRegistries;
import org.bson.codecs.configuration.CodecRegistry;
import org.springframework.stereotype.Repository;

import com.mongodb.MongoClient;
import com.mongodb.MongoClientOptions;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoCursor;
import com.mongodb.client.MongoDatabase;
import com.mongodb.client.model.Filters;

import br.com.apisw.codecs.PlanetaCodec;
import br.com.apisw.models.Planeta;

@Repository
public class PlanetaRepository {

    private MongoClient cliente;
    private MongoDatabase bancoDeDados;

    // metodo que abre a conexão e persiste os dados
    private void criarConexao() {
        // captura o codec de Document
        Codec<Document> codec = MongoClient.getDefaultCodecRegistry().get(Document.class);

        // cria uma instância do PlanetaCodec
        PlanetaCodec planetaCodec = new PlanetaCodec(codec);

        // inclui em um registrador de codecs
        CodecRegistry registro = CodecRegistries.fromRegistries(MongoClient.getDefaultCodecRegistry(),
                CodecRegistries.fromCodecs(planetaCodec));

        // cria um objeto do tipo MongoClientOptions que no momento da conexão com o
        // Mongo, como opção, ele tenha todos os codecs necessários
        MongoClientOptions opcoes = MongoClientOptions.builder().codecRegistry(registro).build();

        // configuração das conexões com o MongoDB
        this.cliente = new MongoClient("localhost:27017", opcoes);
        this.bancoDeDados = cliente.getDatabase("apiSW");
    }

    // fecha a conexao com o MongoBD
    private void fecharConexao() {
        this.cliente.close();
    }

    // metodo salvar onde recebe o objeto planeta
    public void salvar(Planeta planeta) {
        criarConexao();
        MongoCollection<Planeta> planetas = this.bancoDeDados.getCollection("planeta", Planeta.class);
        planetas.insertOne(planeta);

        fecharConexao();
    }

    // metodo listar
    public List<Planeta> obterTodosPlanetas() {
        criarConexao();
        MongoCollection<Planeta> planetas = this.bancoDeDados.getCollection("planeta", Planeta.class);
        MongoCursor<Planeta> resultados = planetas.find().iterator();

        List<Planeta> planetasEncotrados = popularPlanetas(resultados);

        fecharConexao();
        return planetasEncotrados;
    }

    // metodo pesquisar por nome
    public List<Planeta> pesquisarPor(String nome) {
        criarConexao();
        MongoCollection<Planeta> planetaCollection = this.bancoDeDados.getCollection("planeta", Planeta.class);
        MongoCursor<Planeta> resultados = planetaCollection.find(Filters.eq("nome", nome), Planeta.class).iterator();

        List<Planeta> planetas = popularPlanetas(resultados);

        fecharConexao();
        return planetas;
    }

    // metodo pesquisar por ID
    public List<Planeta> pesquisarPorId(String id) {

        criarConexao();
        MongoCollection<Planeta> planetaCollection = this.bancoDeDados.getCollection("planeta", Planeta.class);
        MongoCursor<Planeta> resultados = planetaCollection.find(Filters.eq("_id", id), Planeta.class).iterator();

        List<Planeta> planetas = popularPlanetas(resultados);

        fecharConexao();
        return planetas;
    }

    // metodo que itera sobre os planetas no banco
    private List<Planeta> popularPlanetas(MongoCursor<Planeta> resultados) {
        List<Planeta> planetas = new ArrayList<>();
        while (resultados.hasNext()) {
            planetas.add(resultados.next());
        }
        return planetas;
    }

}

User view in HTML and Thymeleaf:

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8" />
<link type="text/css" rel="stylesheet"
    href="../../materialize/css/materialize.min.css"
    media="screen,projection" />
<link href="https://fonts.googleapis.com/icon?family=Material+Icons"
    rel="stylesheet" />
<title>Sistema Star Wars</title>
<script type="text/javascript"
    src="https://code.jquery.com/jquery-2.1.1.min.js"></script>
</head>
<body class="grey lighten-3">
    <div id="pesquisaPlaneta" class="container">
        <h3 class="main-title center">Pesquisar Planeta</h3>
        <form class="col s12" action="/planeta/pesquisaridplaneta" method="get"> 
            <div class="row">
                <div class="row">
                    <div class="input-field col s12">
                        <input id="id" name="id" type="text" /> <label
                            for="first_name">ID</label>
                    </div>
                </div>

                <div class="row">
                    <div class="input-field col s12 center">
                        <button class="btn waves-effect waves-light" type="submit">Pesquisar</button>
                    </div>
                </div>
            </div>
        </form>
        <div th:if="${planeta} != null">
            <div class="row">
                <div class="input-field col s12">
                    <table class="striped responsive-table">
                        <thead>
                            <tr>
                                <th style="text-align: center;">Nome</th>
                                <th style="text-align: center;">Clima</th>
                                <th style="text-align: center;">Terreno</th>
                            </tr>
                        </thead>
                        <tr th:each="planeta : ${planeta}">
                            <td style="text-align: center;" th:text="${planeta.nome}"></td>
                            <td style="text-align: center;" th:text="${planeta.clima}"></td>
                            <td style="text-align: center;" th:text="${planeta.terreno}"></td>
                            <td style="text-align: center;">
                        </tr>
                    </table>
                </div>
            </div>
        </div>
    </div>
    <!-- Fim do formulario de pesquisa -->

    <script type="text/javascript"
        src="../../materialize/js/materialize.min.js"></script>

</body>
</html>

Example of the page search planets by ID where there is no return of the result:

It does not generate errors and when I debug the return is empty, I am not able to solve this problem, I need help!