Не сохраняется сущность в базу JPA Hibernate

Всем привет. В проекте есть сущность Post с полями:

@Entity(name = "Post")
@Table(name = "POST")
public class Post extends IdEntity{
    private Long id;
    private String message;
    private String location;
    private Date datePosted;
    private User userPosted;
    private User userPagePosted;
    private Set<User> usersTagged;

    public Post() {
    }

    @Id
    @SequenceGenerator(name = "POS_SQ", sequenceName = "POST_SEQ", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "POS_SQ")
    @Column(name = "POST_ID")
    @Override
    public Long getId() {
        return id;
    }

    @Column(name = "MESSAGE", nullable = false)
    public String getMessage() {
        return message;
    }

    @Column(name = "LOCATIONS", nullable = false)
    public String getLocation() {
        return location;
    }

    @Column(name = "DATE_POSTED", nullable = false)
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy")
    public Date getDatePosted() {
        return datePosted;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "ID_USER_POSTED")
    public User getUserPosted() {
        return userPosted;
    }

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "ID_USER_PAGE_POSTED")
    public User getUserPagePosted() {
        return userPagePosted;
    }

    //@JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    @JoinTable(name = "POST_USERS1", joinColumns = @JoinColumn(name = "POST_ID"),
            inverseJoinColumns = @JoinColumn(name = "USER_ID"))
    public Set<User> getUsersTagged() {
        return usersTagged;
    }

    @JsonCreator
    public static Post createFromJson(String jsonString){
        ObjectMapper objectMapper = new ObjectMapper();
        Post post = null;

        try {
            post = objectMapper.readValue(jsonString, Post.class);
        }catch (IOException e){
            e.printStackTrace();
        }
        return post;
    }

     //setters, equals, hashCode and toString don`t give for brevity

Так же есть сущность User:

@Entity(name = "User")
@Table(name = "USERS1")
public class User extends IdEntity{
    private Long id;
    private String firstName;
    private String lastName;
    private String phone;
    private String email;
    private String password;
    private String country;
    private String city;
    private String age;
    private Date dateRegistered;
    private Date dateLastActive;
    private RelationshipType relationship;
    private ReligionType religion;
    private String school;
    private String university;

    private List<Message> messageSent;
    private List<Message> messageReceived;
    private List<Post> posts;
    private Set<Relationship> statuses = new HashSet<>();

    public User() {
    }

    @Id
    @SequenceGenerator(name = "USER_SQ", sequenceName = "USERS1_SEQ", allocationSize = 1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "USER_SQ")
    @Column(name = "USER_ID")
    @Override
    public Long getId() {
        return id;
    }

    @Column(name = "USER_FIRST_NAME", nullable = false)
    public String getFirstName() {
        return firstName;
    }

    @Column(name = "USER_LAST_NAME", nullable = false)
    public String getLastName() {
        return lastName;
    }

    @Column(name = "PHONE", nullable = false)
    public String getPhone() {
        return phone;
    }

    @Column(name = "EMAIL", nullable = false)
    public String getEmail(){ return email; }

    @Column(name = "PASSWORD_USER")
    public String getPassword() {
        return password;
    }

    @Column(name = "COUNTRY", nullable = false)
    public String getCountry() {
        return country;
    }

    @Column(name = "CITY", nullable = false)
    public String getCity() {
        return city;
    }

    @Column(name = "AGE", nullable = false)
    public String getAge() {
        return age;
    }

    @Column(name = "DATE_REGISTERED", nullable = false)
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy")
    public Date getDateRegistered() {
        return dateRegistered;
    }

    @Column(name = "DATE_LAST_ACTIVE", nullable = false)
    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy")
    public Date getDateLastActive() {
        return dateLastActive;
    }

    @Enumerated(EnumType.STRING)
    @Column(name = "RELATIONSHIP_TYPE", nullable = false)
    public RelationshipType getRelationship() {
        return relationship;
    }

    @Enumerated(EnumType.STRING)
    @Column(name = "RELIGION_TYPE", nullable = false)
    public ReligionType getReligion() {
        return religion;
    }

    @Column(name = "SCHOOL", nullable = false)
    public String getSchool() {
        return school;
    }

    @Column(name = "UNIVERSITY", nullable = false)
    public String getUniversity() {
        return university;
    }

    @JsonIgnore
    @OneToMany(mappedBy = "userFrom", fetch = FetchType.LAZY, targetEntity = Message.class)
    public List<Message> getMessageSent() {
        return messageSent;
    }

    @JsonIgnore
    @OneToMany(mappedBy = "userTo", fetch = FetchType.LAZY, targetEntity = Message.class)
    public List<Message> getMessageReceived() {
        return messageReceived;
    }

    @JsonIgnore
    @OneToMany(mappedBy = "userPosted", fetch = FetchType.LAZY, targetEntity = Post.class)
    public List<Post> getPosts() {
        return posts;
    }

    @JsonIgnore
    @ManyToMany(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    @JoinTable(name = "USERS1_RELATIONSHIP", joinColumns = @JoinColumn(name = "USER_ID"),
            inverseJoinColumns = @JoinColumn(name = "RELATION_ID"))
    public Set<Relationship> getStatuses() {
        return statuses;
    }

    public void addRelationship(Relationship relationship){
        statuses.add(relationship);
        relationship.getUsers().add(this);
    }

    public void removeRelationship(Relationship relationship){
        statuses.remove(relationship);
        relationship.getUsers().remove(this);
    }

    @JsonCreator
    public static User createFromJson(String jsonString){
        ObjectMapper objectMapper = new ObjectMapper();
        User user = null;

        try {
            user = objectMapper.readValue(jsonString, User.class);
        }catch (IOException e){
            e.printStackTrace();
        }
        return user;
    }
    //setters, equals, hashCode and toString don`t give for brevity

Без поля Set<User> usersTagged сущность Post сохраняется в базу без проблем. Но после того, как я нахожу отмеченных в сообщении юзеров, заношу их в список и пытаюсь просетить сущности Post полученный список юзеров метод createPost:

public void createPost(Post post)throws BadRequestException, InternalServerError{
        if (!post.getUserPosted().getId().equals(post.getUserPagePosted().getId())){
            checkStatusBetweenUsers(post.getUserPosted().getId(), post.getUserPagePosted().getId());
        }
        validateMessage(post.getMessage());
        Date datePosted = new Date();
        post.setDatePosted(datePosted);
        if (!findUsersTagged(post.getMessage()).isEmpty()){
            post.setUsersTagged(findUsersTagged(post.getMessage()));
        }
        postDAO.save(post);
    }

То получаю ошибку. Тестирую через Postman. Полный вывод ошибки:

<p><b>Type</b> Exception Report</p>
    <p><b>Message</b> Request processing failed; nested exception is javax.persistence.PersistenceException:
        org.hibernate.PersistentObjectException: detached entity passed to persist: com.findme.models.User</p>
    <p><b>Description</b> The server encountered an unexpected condition that prevented it from fulfilling the request.
    </p>
    <p><b>Exception</b></p>
    <pre>org.springframework.web.util.NestedServletException: Request processing failed; nested exception is javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: com.findme.models.User
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1013)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
</pre>
    <p><b>Root Cause</b></p>
    <pre>javax.persistence.PersistenceException: org.hibernate.PersistentObjectException: detached entity passed to persist: com.findme.models.User
    org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:149)
    org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:157)
    org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:164)
    org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:813)
    org.hibernate.internal.SessionImpl.persist(SessionImpl.java:773)
    org.hibernate.jpa.event.internal.core.JpaPersistEventListener$1.cascade(JpaPersistEventListener.java:80)
    org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:467)
    org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:392)
    org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
    org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:500)
    org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:432)
    org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:395)
    org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
    org.hibernate.engine.internal.Cascade.cascade(Cascade.java:126)
    org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:445)
    org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:281)
    org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
    org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
    org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67)
    org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189)
    org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132)
    org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58)
    org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:782)
    org.hibernate.internal.SessionImpl.persist(SessionImpl.java:767)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:308)
    com.sun.proxy.$Proxy48.persist(Unknown Source)
    com.findme.dao.GeneralDAO.save(GeneralDAO.java:27)
    com.findme.dao.GeneralDAO$$FastClassBySpringCGLIB$$bc01b56.invoke(&lt;generated&gt;)
    org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    com.findme.dao.PostDAO$$EnhancerBySpringCGLIB$$f9a4ae71.save(&lt;generated&gt;)
    com.findme.service.PostService.createPost(PostService.java:41)
    com.findme.controller.PostController.addPost(PostController.java:41)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
</pre>
    <p><b>Root Cause</b></p>
    <pre>org.hibernate.PersistentObjectException: detached entity passed to persist: com.findme.models.User
    org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:124)
    org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:806)
    org.hibernate.internal.SessionImpl.persist(SessionImpl.java:773)
    org.hibernate.jpa.event.internal.core.JpaPersistEventListener$1.cascade(JpaPersistEventListener.java:80)
    org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:467)
    org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:392)
    org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
    org.hibernate.engine.internal.Cascade.cascadeCollectionElements(Cascade.java:500)
    org.hibernate.engine.internal.Cascade.cascadeCollection(Cascade.java:432)
    org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:395)
    org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:193)
    org.hibernate.engine.internal.Cascade.cascade(Cascade.java:126)
    org.hibernate.event.internal.AbstractSaveEventListener.cascadeAfterSave(AbstractSaveEventListener.java:445)
    org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:281)
    org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:182)
    org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:125)
    org.hibernate.jpa.event.internal.core.JpaPersistEventListener.saveWithGeneratedId(JpaPersistEventListener.java:67)
    org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:189)
    org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:132)
    org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:58)
    org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:782)
    org.hibernate.internal.SessionImpl.persist(SessionImpl.java:767)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:308)
    com.sun.proxy.$Proxy48.persist(Unknown Source)
    com.findme.dao.GeneralDAO.save(GeneralDAO.java:27)
    com.findme.dao.GeneralDAO$$FastClassBySpringCGLIB$$bc01b56.invoke(&lt;generated&gt;)
    org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
    org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
    org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
    org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    com.findme.dao.PostDAO$$EnhancerBySpringCGLIB$$f9a4ae71.save(&lt;generated&gt;)
    com.findme.service.PostService.createPost(PostService.java:41)
    com.findme.controller.PostController.addPost(PostController.java:41)
    sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    java.lang.reflect.Method.invoke(Method.java:498)
    org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
    org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:882)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
</pre>
    <p><b>Note</b> The full stack trace of the root cause is available in the server logs.</p>
    <hr class="line" />
    <h3>Apache Tomcat/9.0.8</h3>

Не могу понять где проблема. Не правильно заданы отношения между сущностями ? Подскажите, что не так делаю.