Java use streams map to return desired JSON Structure

See if below one helps

roleLevels.stream().collect(Collectors.groupingBy(r -> r.getName()));

See if this helps.

public class ConverToJSON {
public static void main(String[] args) {
    System.out.println(getList());

    final Map<String, Map<String, List<String>>> map = new HashMap<>();

    getList().forEach(roleManager -> getRoleNameList(map, roleManager));
    System.out.println(new JSONObject(map));
}

private static void getRoleNameList(Map<String, Map<String, List<String>>> map, RoleManager roleManager) {
    map.computeIfAbsent(roleManager.getName(), r -> new HashMap<>())
            .computeIfAbsent("role", rn -> new ArrayList<>())
            .add(roleManager.getRole());
}

private static List<RoleManager> getList(){
    List<RoleManager> roles = new ArrayList();
    roles.add(new RoleManager("driver", "Hub"));
    roles.add(new RoleManager("hoc", "org"));
    roles.add(new RoleManager("hubManager", "Hub"));

    return roles;
}

private static class RoleManager {
    final String role;
    final String name;
    public RoleManager(String role, String name) {
        this.role = role;
        this.name = name;
    }

    public String getRole() {
        return role;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {
        return "RoleManager{" +
                "driver='" + role + '\'' +
                ", hub='" + name + '\'' +
                '}';
    }
}

}

Below is the expected result:

{
   "Hub":{
      "role":[
         "driver",
         "hubManager"
      ]
   },
   "org":{
      "role":[
         "hoc"
      ]
   }
}

You have received great answers, but in case the exact specified JSON output is needed, there's another thing we need to do.

Let's first create RoleLevel class:

@Getter
public class RoleLevel {
    String roleName;
    String name;
}

Then we can group by name:

ObjectMapper mapper = new ObjectMapper();
String jsonStr = "[{\"roleName\": \"driver\", \"name\": \"Hub\"},{\"roleName\": \"hoc\", \"name\": \"Org\"},{\"roleName\": \"hubManager\", \"name\": \"Hub\"}]";
    List<RoleLevel> roleLevels = mapper.readValue(jsonStr, new TypeReference<List<RoleLevel>>(){});

Map<String, List<String>> nameToRoles = roleLevels.stream()
        .collect(Collectors.groupingBy(RoleLevel::getName, Collectors.mapping(RoleLevel::getRoleName, Collectors.toList())));

System.out.println(mapper.writeValueAsString(nameToRoles));

But the output JSON is not exactly the expected JSON output:

{
    "Hub": ["driver", "hubManager"], // no "role" field
    "Org": ["hoc"]                   // no "role" field
}

To fix this we need to create a Person class:

@AllArgsConstructor
@Getter
@Setter
public class Person {
    List<String> role;
}

then do:

Map<String, Person> personToRoles = nameToRoles.entrySet()
        .stream()
        .collect(Collectors.toMap(Map.Entry::getKey, entry -> new Person(entry.getValue())));

System.out.println(mapper.writeValueAsString(personToRoles));

Output:

{
    "Hub": {
        "role": ["driver", "hubManager"]
    },
    "Org": {
        "role": ["hoc"]
    }
}