Caused by: org.hibernate.QueryException: Illegal attempt to dereference collection[office0_.officeCode.employees] with element attribute referenced as firstN

I am working on Spring Boot and Spring Data JPA and writing JPQL queries. I am trying to convert the content below the SubQuery to JPQL but I am getting the following error.

mistake:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springBootJpaMysqlComplexApplication': Unsatisfied dependency expressed through field 'officeRepository'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'officeRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Validation failed for query for method public abstract java.util.List com.example.repository.OfficeRepository.findByEmployeesAndOfficeCode()!
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:643) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:116) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:879) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.2.RELEASE.jar:2.2.2.RELEASE]
    at com.example.SpringBootJpaMysqlComplexApplication.main(SpringBootJpaMysqlComplexApplication.java:24) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'officeRepository': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Validation failed for query for method public abstract java.util.List com.example.repository.OfficeRepository.findByEmployeesAndOfficeCode()!
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1796) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:595) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1287) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1207) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:640) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    ... 19 common frames omitted
Caused by: java.lang.IllegalArgumentException: Validation failed for query for method public abstract java.util.List com.example.repository.OfficeRepository.findByEmployeesAndOfficeCode()!
    at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:93) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.SimpleJpaQuery.<init>(SimpleJpaQuery.java:63) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromMethodWithQueryString(JpaQueryFactory.java:76) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryFactory.fromQueryAnnotation(JpaQueryFactory.java:56) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$DeclaredQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:142) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$CreateIfNotFoundQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:209) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.query.JpaQueryLookupStrategy$AbstractQueryLookupStrategy.resolveQuery(JpaQueryLookupStrategy.java:79) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lookupQuery(RepositoryFactorySupport.java:574) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$mapMethodsToQuery$1(RepositoryFactorySupport.java:567) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193) ~[na:1.8.0_171]
    at java.util.Iterator.forEachRemaining(Iterator.java:116) ~[na:1.8.0_171]
    at java.util.Collections$UnmodifiableCollection$1.forEachRemaining(Collections.java:1049) ~[na:1.8.0_171]
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801) ~[na:1.8.0_171]
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481) ~[na:1.8.0_171]
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471) ~[na:1.8.0_171]
    at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708) ~[na:1.8.0_171]
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[na:1.8.0_171]
    at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499) ~[na:1.8.0_171]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.mapMethodsToQuery(RepositoryFactorySupport.java:569) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$new$0(RepositoryFactorySupport.java:559) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at java.util.Optional.map(Optional.java:215) ~[na:1.8.0_171]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.<init>(RepositoryFactorySupport.java:559) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactorySupport.getRepository(RepositoryFactorySupport.java:332) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.lambda$afterPropertiesSet$5(RepositoryFactoryBeanSupport.java:297) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.util.Lazy.getNullable(Lazy.java:212) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.util.Lazy.get(Lazy.java:94) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.repository.core.support.RepositoryFactoryBeanSupport.afterPropertiesSet(RepositoryFactoryBeanSupport.java:300) ~[spring-data-commons-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.data.jpa.repository.support.JpaRepositoryFactoryBean.afterPropertiesSet(JpaRepositoryFactoryBean.java:121) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1855) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1792) ~[spring-beans-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    ... 29 common frames omitted
Caused by: java.lang.IllegalArgumentException: org.hibernate.QueryException: illegal attempt to dereference collection [office0_.officeCode.employees] with element property reference [firstName] [SELECT o.employees.firstName, o.employees.lastName FROM com.example.entity.Office o WHERE o.country='USA']
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:138) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:718) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:23) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at sun.reflect.GeneratedMethodAccessor44.invoke(Unknown Source) ~[na:na]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_171]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_171]
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:368) ~[spring-orm-5.2.2.RELEASE.jar:5.2.2.RELEASE]
    at com.sun.proxy.$Proxy89.createQuery(Unknown Source) ~[na:na]
    at org.springframework.data.jpa.repository.query.SimpleJpaQuery.validateQuery(SimpleJpaQuery.java:87) ~[spring-data-jpa-2.2.3.RELEASE.jar:2.2.3.RELEASE]
    ... 58 common frames omitted
Caused by: org.hibernate.QueryException: illegal attempt to dereference collection [office0_.officeCode.employees] with element property reference [firstName] [SELECT o.employees.firstName, o.employees.lastName FROM com.example.entity.Office o WHERE o.country='USA']
    at org.hibernate.QueryException.generateQueryException(QueryException.java:120) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.QueryException.wrapWithQueryString(QueryException.java:103) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:220) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:144) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:113) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.engine.query.spi.HQLQueryPlan.<init>(HQLQueryPlan.java:73) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.engine.query.spi.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:155) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.getQueryPlan(AbstractSharedSessionContract.java:600) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:709) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    ... 65 common frames omitted
Caused by: org.hibernate.QueryException: illegal attempt to dereference collection [office0_.officeCode.employees] with element property reference [firstName]
    at org.hibernate.hql.internal.ast.tree.DotNode$1.buildIllegalCollectionDereferenceException(DotNode.java:59) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.checkLhsIsNotCollection(DotNode.java:643) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.resolve(DotNode.java:252) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:114) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:109) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:104) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.resolveSelectExpression(DotNode.java:786) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.HqlSqlWalker.resolveSelectExpression(HqlSqlWalker.java:1057) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2295) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2232) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1503) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:585) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:313) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:261) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:272) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:192) ~[hibernate-core-5.4.9.Final.jar:5.4.9.Final]
    ... 71 common frames omitted

Inquire:

SELECT 
    lastName, firstName
FROM
    employees
WHERE
    officeCode IN (SELECT 
            officeCode
        FROM
            offices
        WHERE
            country = 'USA');

Repository - I'd like to utilize object graphs, since entities associated with each other definitely get data.

public interface OfficeRepository extends JpaRepository<Office, String>{
    @Query("SELECT o.employees.firstName, o.employees.lastName FROM Office o WHERE o.country='USA'")
    List<Object[]> findByEmployeesAndOfficeCode();
}

Entity - Office:

@Entity
@Table(name="offices")
@NamedQuery(name="Office.findAll", query="SELECT o FROM Office o")
public class Office implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(unique=true, nullable=false, length=10)
    private String officeCode;

    @Column(nullable=false, length=50)
    private String addressLine1;

    @Column(length=50)
    private String addressLine2;

    @Column(nullable=false, length=50)
    private String city;

    @Column(nullable=false, length=50)
    private String country;

    @Column(nullable=false, length=50)
    private String phone;

    @Column(nullable=false, length=15)
    private String postalCode;

    @Column(length=50)
    private String state;

    @Column(nullable=false, length=10)
    private String territory;

    //bi-directional many-to-one association to Employee
    @OneToMany(mappedBy="office")
    private List<Employee> employees;

    public Office() {
    }

    public String getOfficeCode() {
        return this.officeCode;
    }

    public void setOfficeCode(String officeCode) {
        this.officeCode = officeCode;
    }

    public String getAddressLine1() {
        return this.addressLine1;
    }

    public void setAddressLine1(String addressLine1) {
        this.addressLine1 = addressLine1;
    }

    public String getAddressLine2() {
        return this.addressLine2;
    }

    public void setAddressLine2(String addressLine2) {
        this.addressLine2 = addressLine2;
    }

    public String getCity() {
        return this.city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getCountry() {
        return this.country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getPhone() {
        return this.phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getPostalCode() {
        return this.postalCode;
    }

    public void setPostalCode(String postalCode) {
        this.postalCode = postalCode;
    }

    public String getState() {
        return this.state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getTerritory() {
        return this.territory;
    }

    public void setTerritory(String territory) {
        this.territory = territory;
    }

    public List<Employee> getEmployees() {
        return this.employees;
    }

    public void setEmployees(List<Employee> employees) {
        this.employees = employees;
    }

    public Employee addEmployee(Employee employee) {
        getEmployees().add(employee);
        employee.setOffice(this);

        return employee;
    }

    public Employee removeEmployee(Employee employee) {
        getEmployees().remove(employee);
        employee.setOffice(null);

        return employee;
    }
}

Entity - Employee:

@Entity
@Table(name="employees")
@NamedQuery(name="Employee.findAll", query="SELECT e FROM Employee e")
public class Employee implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(unique=true, nullable=false)
    private int employeeNumber;

    @Column(nullable=false, length=100)
    private String email;

    @Column(nullable=false, length=10)
    private String extension;

    @Column(nullable=false, length=50)
    private String firstName;

    @Column(nullable=false, length=50)
    private String jobTitle;

    @Column(nullable=false, length=50)
    private String lastName;

    //bi-directional many-to-one association to Customer
    @OneToMany(mappedBy="employee")
    private List<Customer> customers;

    //bi-directional many-to-one association to Employee
    @ManyToOne
    @JoinColumn(name="reportsTo")
    private Employee employee;

    //bi-directional many-to-one association to Employee
    @OneToMany(mappedBy="employee")
    private List<Employee> employees;

    //bi-directional many-to-one association to Office
    @ManyToOne
    @JoinColumn(name="officeCode", nullable=false)
    private Office office;

    public Employee() {
    }

    public int getEmployeeNumber() {
        return this.employeeNumber;
    }

    public void setEmployeeNumber(int employeeNumber) {
        this.employeeNumber = employeeNumber;
    }

    public String getEmail() {
        return this.email;
    }

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

    public String getExtension() {
        return this.extension;
    }

    public void setExtension(String extension) {
        this.extension = extension;
    }

    public String getFirstName() {
        return this.firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getJobTitle() {
        return this.jobTitle;
    }

    public void setJobTitle(String jobTitle) {
        this.jobTitle = jobTitle;
    }

    public String getLastName() {
        return this.lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public List<Customer> getCustomers() {
        return this.customers;
    }

    public void setCustomers(List<Customer> customers) {
        this.customers = customers;
    }

    public Customer addCustomer(Customer customer) {
        getCustomers().add(customer);
        customer.setEmployee(this);

        return customer;
    }

    public Customer removeCustomer(Customer customer) {
        getCustomers().remove(customer);
        customer.setEmployee(null);

        return customer;
    }

    public Employee getEmployee() {
        return this.employee;
    }

    public void setEmployee(Employee employee) {
        this.employee = employee;
    }

    public List<Employee> getEmployees() {
        return this.employees;
    }

    public void setEmployees(List<Employee> employees) {
        this.employees = employees;
    }

    public Employee addEmployee(Employee employee) {
        getEmployees().add(employee);
        employee.setEmployee(this);

        return employee;
    }

    public Employee removeEmployee(Employee employee) {
        getEmployees().remove(employee);
        employee.setEmployee(null);

        return employee;
    }

    public Office getOffice() {
        return this.office;
    }

    public void setOffice(Office office) {
        this.office = office;
    }
}