java.sql.SQLIntegrityConstraintViolationException: ORA-01400: cannot insert NULL into Column Name - spring-boot

Question

I'm getting this error whenever I tried to post data from postman.
There are two tables - User-details and Vehicle-details.
I'm doing the One To Many Mapping
Error: java.sql.SQLIntegrityConstraintViolationException: ORA-01400: cannot insert NULL into ("SYSTEM"."USER_DETAIL"."U_ID")
User_details.java
import javax.persistence.Entity;
import javax.persistence.Id;
import java.util.List;
import javax.persistence.*;
#Entity
#Table(name = "User_Detail")
public class UserDetails {
#Id
#Column(name="user_id")
int u_id;
String u_name;
String u_email;
int mob_no;
String gender;
int age;
String city;
String State;
int pincode;
String address;
String password;
#OneToMany(cascade = CascadeType.ALL)
#JoinColumn(name="fk_user_id",referencedColumnName = "user_id")
private List<Vehicle> vehicle;
}
Vehicle.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
import org.hibernate.annotations.GeneratorType;
#Entity
#Table(name="Vehicle_detail")
public class Vehicle {
#Id
#Column(name="vehicle_id")
private int vid;
private String vname;
private String vmodel;
private String showroomprice;
private String onroadprice;
private long aadharcardno;
private String pancardno;
private boolean photo;
private String employmenttypes;
private boolean salaryslip;
private int annualsalary;
private boolean existingemi;
}
Error:
java.sql.SQLIntegrityConstraintViolationException: ORA-01400: cannot insert NULL into ("SYSTEM"."USER_DETAIL"."U_ID")
at oracle.jdbc.driver.SQLStateMapping.newSQLException(SQLStateMapping.java:85) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.DatabaseError.newSQLException(DatabaseError.java:133) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:206) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:455) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.T4CTTIoer.processError(T4CTTIoer.java:413) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.T4C8Oall.receive(T4C8Oall.java:1034) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.T4CPreparedStatement.doOall8(T4CPreparedStatement.java:194) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.T4CPreparedStatement.executeForRows(T4CPreparedStatement.java:953) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:1222) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3387) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:3468) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at oracle.jdbc.driver.OraclePreparedStatementWrapper.executeUpdate(OraclePreparedStatementWrapper.java:1350) ~[ojdbc6.jar:Oracle JDBC Driver version - "11.1.0.7.0-Production"]
at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61) ~[HikariCP-4.0.3.jar:na]
at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java) ~[HikariCP-4.0.3.jar:na]
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:46) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3375) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3908) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:107) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:604) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.engine.spi.ActionQueue.lambda$executeActions$1(ActionQueue.java:478) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at java.base/java.util.LinkedHashMap.forEach(LinkedHashMap.java:721) ~[na:na]
at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:475) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:344) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:40) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:107) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1407) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:489) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3290) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2425) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:449) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:183) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:40) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:281) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:101) ~[hibernate-core-5.6.11.Final.jar:5.6.11.Final]
at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:562) ~[spring-orm-5.3.23.jar:5.3.23]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:743) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:711) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:654) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:407) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:119) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.23.jar:5.3.23]
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:137) ~[spring-tx-5.3.23.jar:5.3.23]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.23.jar:5.3.23]
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174) ~[spring-data-jpa-2.7.3.jar:2.7.3]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.23.jar:5.3.23]
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97) ~[spring-aop-5.3.23.jar:5.3.23]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) ~[spring-aop-5.3.23.jar:5.3.23]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215) ~[spring-aop-5.3.23.jar:5.3.23]
at jdk.proxy2/jdk.proxy2.$Proxy105.save(Unknown Source) ~[na:na]
I'm trying to Post Data via Postman.