spring boot - How to implement pessimistic locking in the SpringBoot app (Maven) -

i've been trying implement pessimistic locking in springboot app. questions are:

1. do need add persistence.xml or possible add in pom.xml, if yes how?
2. if need add persistence.xml how should like? have tried approach , keep getting error: "this configuration disallows runtime optimization, following listed types not enhanced @ build time or @ class load time javaagent:.... "

i have implemented optimistic locking before , have added @version , couple of more lines. why pessimistic locking complicated? doing wrong?

these dependencies

<dependencies>         <dependency>             <groupid>org.springframework.boot</groupid>             <artifactid>spring-boot-starter-data-jpa</artifactid>         </dependency>         <dependency>             <groupid>org.springframework.boot</groupid>             <artifactid>spring-boot-starter-mail</artifactid>         </dependency>         <dependency>             <groupid>org.springframework.boot</groupid>             <artifactid>spring-boot-starter-web</artifactid>         </dependency>         <dependency>             <groupid>com.h2database</groupid>             <artifactid>h2</artifactid>             <scope>runtime</scope>         </dependency>         <dependency>             <groupid>org.springframework.boot</groupid>             <artifactid>spring-boot-starter-test</artifactid>             <scope>test</scope>         </dependency>         <dependency>             <groupid>io.jsonwebtoken</groupid>             <artifactid>jjwt</artifactid>             <version>0.6.0</version>         </dependency>         <dependency>             <groupid>mysql</groupid>             <artifactid>mysql-connector-java</artifactid>             <scope>runtime</scope>         </dependency>         <dependency>             <groupid>org.postgresql</groupid>             <artifactid>postgresql</artifactid>         </dependency>         <dependency>             <groupid>javax.persistence</groupid>             <artifactid>persistence-api</artifactid>             <version>1.0</version>         </dependency> </dependencies> 

and service

  @autowired   entitymanager em;     @transactional     public reservation createreservation(reservationdto reservationdto) {     ........     ........     (string id : ids) {             table table = em.find(table.class, long.parselong(id));             em.lock(table, lockmodetype.pessimistic_write);              em.refresh(table);             tablerepository.save(table);     ......... 

and controller

    .......         try {          reservation reservation = reservationservice.createreservation(reservationdto);          if (reservation == null){               return new responseentity(httpstatus.bad_request);          }          emailservice.sendmailinvite(reservation, guest);          return new responseentity(httpstatus.ok);     }catch (pessimisticlockexception e){          return new responseentity(httpstatus.bad_request);     }     ....... 

thank you!