Validation failed for classes during persist time for groups

Question

i'm trying to run a Springboot app and while testing it with Postman I get an error message related to the following class:

Package com.portfolio.jwt.Security.Entity;

import jakarta.persistence.Column;
import jakarta.persistence.Entity;
import jakarta.persistence.FetchType;
import jakarta.persistence.GeneratedValue;
import jakarta.persistence.GenerationType;
import jakarta.persistence.Id;
import jakarta.persistence.JoinColumn;
import jakarta.persistence.JoinTable;
import jakarta.persistence.ManyToMany;
import jakarta.validation.constraints.NotNull;
import java.util.HashSet;
import java.util.Set;

@Entity
public class Usuario {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;
    @NotNull
    private String nombre;
    @NotNull
    @Column(unique = true)
    private String nombreUsuario;
    @NotNull
    private String email;
    @NotNull
    private String password;
    @ManyToMany(fetch = FetchType.EAGER)
    @JoinTable(name = "usuario_rol", joinColumns = @JoinColumn(name = "usuario_id"), inverseJoinColumns = @JoinColumn(name = "rol_id"))
    private Set<Rol> roles = new HashSet<>();
    
    //Constructores

    public Usuario() {
    }

    public Usuario(String nombre, String nombreUsuario, String email, String password) {
        this.nombre = nombre;
        this.nombreUsuario = nombreUsuario;
        this.email = email;
        this.password = password;
    }
    
    //Getters y Setters

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getNombre() {
        return nombre;
    }

    public void setNombre(String nombre) {
        this.nombre = nombre;
    }

    public String getNombreUsuario() {
        return nombreUsuario;
    }

    public void setNombreUsuario(String nombreUsuario) {
        this.nombreUsuario = nombreUsuario;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Set<Rol> getRoles() {
        return roles;
    }

    public void setRoles(Set<Rol> roles) {
        this.roles = roles;
    }
    
}

This is the error message:

{
    "timestamp": "2023-04-21T16:21:22.533+00:00",
    "status": 500,
    "error": "Internal Server Error",
    "trace": "jakarta.validation.ConstraintViolationException: Validation failed for classes [com.portfolio.jwt.Security.Entity.Usuario] during persist time for groups [jakarta.validation.groups.Default, ]\nList of constraint violations:[\n\tConstraintViolationImpl{interpolatedMessage='no debe ser nulo', propertyPath=nombreUsuario, rootBeanClass=class 
com.portfolio.jwt.Security.Entity.Usuario, 
messageTemplate='{jakarta.validation.constraints.NotNull.message}'}\n]\r\n\tat 
org.hibernate.cfg.beanvalidation.BeanValidationEventListener.validate(BeanValidationEventListener.java:148)\r\n\tat 
org.hibernate.cfg.beanvalidation.BeanValidationEventListener.onPreInsert(BeanValidationEventListener.java:80)\r\n\tat 
org.hibernate.action.internal.EntityIdentityInsertAction.preInsert(EntityIdentityInsertAction.java:184)\r\n\tat 
org.hibernate.action.internal.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:74)\r\n\tat 
org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:653)\r\n\tat 
org.hibernate.engine.spi.ActionQueue.addResolvedEntityInsertAction(ActionQueue.java:283)\r\n\tat 
org.hibernate.engine.spi.ActionQueue.addInsertAction(ActionQueue.java:264)\r\n\tat 
org.hibernate.engine.spi.ActionQueue.addAction(ActionQueue.java:322)\r\n\tat 
org.hibernate.event.internal.AbstractSaveEventListener.addInsertAction(AbstractSaveEventListener.java:340)\r\n\tat 
org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:286)\r\n\tat 
org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:192)\r\n\tat 
org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:122)\r\n\tat 
org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:184)\r\n\tat 
org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:129)\r\n\tat 
org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:53)\r\n\tat 
org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107)\r\n\tat 
org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:735)\r\n\tat 
org.hibernate.internal.SessionImpl.persist(SessionImpl.java:719)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)\r\n\tat 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat 
java.base/java.lang.reflect.Method.invoke(Method.java:568)\r\n\tat 
org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:360)\r\n\tat jdk.proxy13/jdk.proxy13.$Proxy186.persist(Unknown Source)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)\r\n\tat 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat 
java.base/java.lang.reflect.Method.invoke(Method.java:568)\r\n\tat org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:307)\r\n\tat jdk.proxy13/jdk.proxy13.$Proxy186.persist(Unknown Source)\r\n\tat 
org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:610)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)\r\n\tat 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat 
java.base/java.lang.reflect.Method.invoke(Method.java:568)\r\n\tat org.springframework.data.repository.core.support.RepositoryMethodInvoker$RepositoryFragmentMethodInvoker.lambda$new$0(RepositoryMethodInvoker.java:288)\r\n\tat 
org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:136)\r\n\tat 
org.springframework.data.repository.core.support.RepositoryMethodInvoker.invoke(RepositoryMethodInvoker.java:120)\r\n\tat 
org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:516)\r\n\tat org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:285)\r\n\tat 
org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:628)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.doInvoke(QueryExecutorMethodInterceptor.java:168)\r\n\tat org.springframework.data.repository.core.support.QueryExecutorMethodInterceptor.invoke(QueryExecutorMethodInterceptor.java:143)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:77)\r\n\tat org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)\r\n\tat 
org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)\r\n\tat 
org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:163)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:218)\r\n\tat 
jdk.proxy13/jdk.proxy13.$Proxy188.save(Unknown Source)\r\n\tat 
com.portfolio.jwt.Security.Service.UsuarioService.save(UsuarioService.java:32)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)\r\n\tat 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat 
java.base/java.lang.reflect.Method.invoke(Method.java:568)\r\n\tat org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:343)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:196)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)\r\n\tat 
org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:752)\r\n\tat 
org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:123)\r\n\tat org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:388)\r\n\tat org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119)\r\n\tat 
org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:184)\r\n\tat 
org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.proceed(CglibAopProxy.java:752)\r\n\tat org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:703)\r\n\tat 
com.portfolio.jwt.Security.Service.UsuarioService$$SpringCGLIB$$0.save(<generated>)\r\n\tat 
com.portfolio.jwt.Security.Controller.AuthController.nuevo(AuthController.java:69)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)\r\n\tat 
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)\r\n\tat 
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)\r\n\tat 
java.base/java.lang.reflect.Method.invoke(Method.java:568)\r\n\tat org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:207)\r\n\tat 
org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:152)\r\n\tat 
org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)\r\n\tat 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:884)\r\n\tat 
org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:797)\r\n\tat 
org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)\r\n\tat org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1080)\r\n\tat 
org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:973)\r\n\tat 
org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1003)\r\n\tat 
org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:895)\r\n\tat 
jakarta.servlet.http.HttpServlet.service(HttpServlet.java:705)\r\n\tat 
org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:880)\r\n\tat 
jakarta.servlet.http.HttpServlet.service(HttpServlet.java:814)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:223)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:110)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.springframework.security.web.FilterChainProxy.lambda$doFilterInternal$3(FilterChainProxy.java:231)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:365)\r\n\tat 
org.springframework.security.web.access.intercept.AuthorizationFilter.doFilter(AuthorizationFilter.java:100)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:126)\r\n\tat 
org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:120)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:131)\r\n\tat 
org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:85)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:100)\r\n\tat org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:179)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
com.portfolio.jwt.Security.jwt.JwtTokenFilter.doFilterInternal(JwtTokenFilter.java:42)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:107)\r\n\tat 
org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:93)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:91)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)\r\n\tat 
org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.context.SecurityContextHolderFilter.doFilterInternal(SecurityContextHolderFilter.java:69)\r\n\tat org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:62)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:374)\r\n\tat 
org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:233)\r\n\tat 
org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:191)\r\n\tat 
org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:351)\r\n\tat 
org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267)\r\n\tat 

org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)\r\n\tat 
org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:185)\r\n\tat 
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:158)\r\n\tat 
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197)\r\n\tat 
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)\r\n\tat 
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)\r\n\tat 
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:119)\r\n\tat 
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)\r\n\tat 
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)\r\n\tat 
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:357)\r\n\tat 
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:400)\r\n\tat 
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)\r\n\tat 
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861)\r\n\tat 
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1739)\r\n\tat 
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52)\r\n\tat 
org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)\r\n\tat 
org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)\r\n\tat 
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)\r\n\tat 
java.base/java.lang.Thread.run(Thread.java:833)\r\n",
    "message": "Validation failed for classes 
[com.portfolio.jwt.Security.Entity.Usuario] during persist time for 
groups [jakarta.validation.groups.Default, ]\nList of constraint 
violations:[\n\tConstraintViolationImpl{interpolatedMessage='no debe
 ser nulo', propertyPath=nombreUsuario, rootBeanClass=class 
com.portfolio.jwt.Security.Entity.Usuario, 
messageTemplate='{jakarta.validation.constraints.NotNull.message}'}\n
]",
    "path": "/auth/nuevo"
}

There's a NotNull validation which apparently throws an error related to "nombreUsuario" field what I cannot see where's the problem. Sorry, maybe is a foolish mistake but I'm new to backend programming an don't fully know the whole structure to trace back the error correctly.