[JAVA-2306] Fixes after Loredana's review

* Brought back UserRepositoryCustomImpl.java

* Added link to https://www.baeldung.com/spring-data-jpa-query in spring-data-jpa-query-2 README

* Migrated code for https://www.baeldung.com/spring-data-jpa-query-by-date

* Migrated https://www.baeldung.com/spring-vs-jta-transactional to spring-persistence-simple

persistence-modules/spring-persistence-simple/README.md

@@ -5,6 +5,7 @@
 
 ### Relevant Articles: 
 - [Transaction Propagation and Isolation in Spring @Transactional](https://www.baeldung.com/spring-transactional-propagation-isolation)
+- [JTA Transaction with Spring](https://www.baeldung.com/spring-vs-jta-transactional)
 - [Mock JNDI Datasource](https://www.baeldung.com/spring-mock-jndi-datasource)
 
 ### Eclipse Config 

persistence-modules/spring-persistence-simple/pom.xml

@@ -26,6 +26,31 @@
         </dependency>
 
         <!-- persistence -->
+        <dependency>
+            <groupId>javax.persistence</groupId>
+            <artifactId>javax.persistence-api</artifactId>
+            <version>${persistence-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.data</groupId>
+            <artifactId>spring-data-jpa</artifactId>
+            <version>${spring-data-jpa.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.transaction</groupId>
+            <artifactId>javax.transaction-api</artifactId>
+            <version>${transaction-api.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-tx</artifactId>
+            <version>${org.springframework.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter</artifactId>
+            <version>${spring-boot-starter.version}</version>
+        </dependency>
         <dependency>
             <groupId>com.h2database</groupId>
             <artifactId>h2</artifactId>
@@ -58,7 +83,11 @@
     <properties>
         <!-- Spring -->
         <org.springframework.version>5.2.4.RELEASE</org.springframework.version>
+        <spring-boot-starter.version>2.3.3.RELEASE</spring-boot-starter.version>
         <!-- persistence -->
+        <persistence-api.version>2.2</persistence-api.version>
+        <transaction-api.version>1.3</transaction-api.version>
+        <spring-data-jpa.version>2.2.7.RELEASE</spring-data-jpa.version>
         <h2.version>1.4.200</h2.version>
         <!-- simple-jndi -->
         <simple-jndi.version>0.23.0</simple-jndi.version>

persistence-modules/spring-persistence-simple/src/main/java/com/baeldung/spring/transactional/Car.java

@@ -0,0 +1,60 @@
+package com.baeldung.spring.transactional;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class Car {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    private String make;
+
+    private String model;
+
+    public Car() {
+    }
+
+    public Car(Long id, String make, String model) {
+        this.id = id;
+        this.make = make;
+        this.model = model;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getMake() {
+        return make;
+    }
+
+    public void setMake(String make) {
+        this.make = make;
+    }
+
+    public String getModel() {
+        return model;
+    }
+
+    public void setModel(String model) {
+        this.model = model;
+    }
+
+    @Override
+    public String toString() {
+        return "Car{" +
+                "id=" + id +
+                ", make='" + make + '\'' +
+                ", model='" + model + '\'' +
+                '}';
+    }
+}

persistence-modules/spring-persistence-simple/src/main/java/com/baeldung/spring/transactional/CarRepository.java

@@ -0,0 +1,6 @@
+package com.baeldung.spring.transactional;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface CarRepository extends JpaRepository<Car, Long> {
+}

persistence-modules/spring-persistence-simple/src/main/java/com/baeldung/spring/transactional/CarService.java

@@ -0,0 +1,23 @@
+package com.baeldung.spring.transactional;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Isolation;
+import org.springframework.transaction.annotation.Propagation;
+import org.springframework.transaction.annotation.Transactional;
+
+import javax.persistence.EntityExistsException;
+
+@Service
+@Transactional(isolation = Isolation.READ_COMMITTED, propagation = Propagation.SUPPORTS, readOnly = false, timeout = 30)
+public class CarService {
+
+    @Autowired
+    private CarRepository carRepository;
+
+    @Transactional(rollbackFor = IllegalArgumentException.class, noRollbackFor = EntityExistsException.class,
+      rollbackForClassName = "IllegalArgumentException", noRollbackForClassName = "EntityExistsException")
+    public Car save(Car car) {
+        return carRepository.save(car);
+    }
+}

persistence-modules/spring-persistence-simple/src/main/java/com/baeldung/spring/transactional/RentalService.java

@@ -0,0 +1,20 @@
+package com.baeldung.spring.transactional;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import javax.persistence.EntityExistsException;
+import javax.transaction.Transactional;
+
+@Service
+@Transactional(Transactional.TxType.SUPPORTS)
+public class RentalService {
+
+    @Autowired
+    private CarRepository carRepository;
+
+    @Transactional(rollbackOn = IllegalArgumentException.class, dontRollbackOn = EntityExistsException.class)
+    public Car rent(Car car) {
+        return carRepository.save(car);
+    }
+}