Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string

I am getting an error because the parseInt operation receives a null value while connecting to the database. How can i solve it

Customer class

package com.mc_es.spring.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "Customer")
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;

    @Column(name = "first_name")
    private String firstName;

    @Column(name = "last_name")
    private String lastName;

    @Column(name = "email")
    private String email;

    public Customer() {

    }

    public int getId() {
        return id;
    }

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

    public String getFirstName() {
        return firstName;
    }

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

    public String getLastName() {
        return lastName;
    }

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

    public String getEmail() {
        return email;
    }

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

    @Override
    public String toString() {
        return "Customer [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
    }

}

CustomerRest class

package com.mc_es.spring.rest;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.mc_es.spring.business.CustomerService;
import com.mc_es.spring.entity.Customer;

@RestController
@RequestMapping(value = "/api")
public class CustomerRestController {

    @Autowired
    private CustomerService customerService;

    @GetMapping(value = "/customers")
    public List<Customer> getCustomers() {
        return customerService.getCustomers();
    }
}

appConfig class

package com.mc_es.spring.config;

import java.beans.PropertyVetoException;
import java.util.Properties;
import java.util.logging.Logger;

import javax.sql.DataSource;

import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.orm.hibernate5.HibernateTransactionManager;
import org.springframework.orm.hibernate5.LocalSessionFactoryBean;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;

import com.mchange.v2.c3p0.ComboPooledDataSource;

@Configuration
@EnableWebMvc
@EnableTransactionManagement
@ComponentScan(basePackages = "com.mc_es.spring")
@PropertySource(value = { "classpath:persistence-sqlServer.properties" })
public class AppConfig implements WebMvcConfigurer {

    @Autowired
    private Environment environment;
    private Logger logger = Logger.getLogger(getClass().getName());

    @Bean
    public DataSource dataSource() {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();

        try {
            dataSource.setDriverClass("com.microsoft.sqlserver.jdbc.SQLServerDriver");
        } catch (PropertyVetoException exc) {
            throw new RuntimeException(exc);
        }

        logger.info("jdbc.url=" + environment.getProperty("jdbc.url"));
        logger.info("jdbc.user=" + environment.getProperty("jdbc.user"));

        dataSource.setJdbcUrl(environment.getProperty("jdbc.url"));
        dataSource.setUser(environment.getProperty("jdbc.user"));
        dataSource.setPassword(environment.getProperty("jdbc.password"));

        dataSource.setInitialPoolSize(getIntProperty("connection.pool.initialPoolSize"));
        dataSource.setMinPoolSize(getIntProperty("connection.pool.minPoolSize"));
        dataSource.setMaxPoolSize(getIntProperty("connection.pool.maxSize"));
        dataSource.setMaxIdleTime(getIntProperty("connection.pool.maxIdTime"));

        return dataSource;
    }

    private Properties getHibernateProperties() {
        Properties properties = new Properties();

        properties.setProperty("hibernate.dialect", environment.getProperty("hibernate.dialect"));
        properties.setProperty("hibernate.show_sql", environment.getProperty("hibernate.show_sql"));

        return properties;
    }

    private int getIntProperty(String propName) {
        String propValue = environment.getProperty(propName);

        int intPropValue = Integer.parseInt(propValue);

        return intPropValue;
    }

    @Bean
    public LocalSessionFactoryBean sessionFactory() {
        LocalSessionFactoryBean sessionFactory = new LocalSessionFactoryBean();

        sessionFactory.setDataSource(dataSource());
        sessionFactory.setPackagesToScan(environment.getProperty("hibernate.packagesToScan"));
        sessionFactory.setHibernateProperties(getHibernateProperties());

        return sessionFactory;
    }

    @Bean
    @Autowired
    public HibernateTransactionManager transactionManager(SessionFactory sessionFactory) {
        HibernateTransactionManager txManager = new HibernateTransactionManager();
        txManager.setSessionFactory(sessionFactory);

        return txManager;
    }
}

persistence-sqlServer.properties file

jdbc.driver = com.microsoft.sqlserver.jdbc.SQLServerDriver
jdbc.url = jdbc:sqlserver://LOCALHOST:1433;databaseName=App;encrypt=true;trustServerCertificate=true
jdbc.user = SA
jdbc.password = 12345

# Connection pool properties

connection.pool.initialPoolSize = 5
connection.pool.minPoolSize = 5
connection.pool.maxPoolSize = 20
connection.pool.maxIdleTime = 3000

# Hibernate properties

hibernate.dialect = org.hibernate.dialect.SQLServerDialect
hibernate.show_sql = true
hibernate.packagesToScan = com.mc_es.spring.entity

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mc_es</groupId>
    <artifactId>SpringCrmRest</artifactId>
    <version>1.0</version>
    <packaging>war</packaging>

    <properties>
        <spring-webmvc.version>5.3.23</spring-webmvc.version>
        <spring-tx.version>5.3.23</spring-tx.version>
        <spring-orm.version>5.3.23</spring-orm.version>
        <jackson-databind.version>2.13.4</jackson-databind.version>
        <hibernate-core.version>5.6.10.Final</hibernate-core.version>
        <mssql-jdbc.version>11.2.1.jre18</mssql-jdbc.version>
        <c3p0.version>0.9.5.5</c3p0.version>
        <javax.servlet-api.version>4.0.1</javax.servlet-api.version>
        <javax.servlet.jsp-api.version>2.3.3</javax.servlet.jsp-api.version>
        <jaxb-api.version>2.3.1</jaxb-api.version>
    </properties>
    <dependencies>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring-webmvc.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/org.springframework/spring-tx -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>${spring-tx.version}</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/org.springframework/spring-orm -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring-orm.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.fasterxml.jackson.core/jackson-databind -->
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>${jackson-databind.version}</version>
        </dependency>


        <!-- https://mvnrepository.com/artifact/org.hibernate/hibernate-core -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate-core.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.microsoft.sqlserver/mssql-jdbc -->
        <dependency>
            <groupId>com.microsoft.sqlserver</groupId>
            <artifactId>mssql-jdbc</artifactId>
            <version>${mssql-jdbc.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.mchange/c3p0 -->
        <dependency>
            <groupId>com.mchange</groupId>
            <artifactId>c3p0</artifactId>
            <version>${c3p0.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>${javax.servlet-api.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>javax.servlet.jsp-api</artifactId>
            <version>${javax.servlet.jsp-api.version}</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/javax.xml.bind/jaxb-api -->
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>${jaxb-api.version}</version>
        </dependency>

    </dependencies>
    <build>
        <finalName>SpringCrmRest</finalName>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <release>18</release>
                </configuration>
            </plugin>
            <plugin>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.3</version>
            </plugin>
        </plugins>
    </build>
</project>

Exception: It says there is an error in the parseInt operation. I am only doing the parse operation in the AppConfig file.

WARNING: Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'customerManager': Unsatisfied dependency expressed through field 'customerDAO'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'hibernateCustomerDAO': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.hibernate5.LocalSessionFactoryBean]: Factory method 'sessionFactory' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
Eki 10, 2022 8:28:58 �S org.springframework.web.servlet.FrameworkServlet initServletBean
SEVERE: Context initialization failed
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'customerManager': Unsatisfied dependency expressed through field 'customerDAO'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'hibernateCustomerDAO': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.hibernate5.LocalSessionFactoryBean]: Factory method 'sessionFactory' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:955)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:918)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583)
    at org.springframework.web.servlet.FrameworkServlet.configureAndRefreshWebApplicationContext(FrameworkServlet.java:702)
    at org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:578)
    at org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:530)
    at org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:170)
    at javax.servlet.GenericServlet.init(GenericServlet.java:158)
    at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1164)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1013)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4958)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5265)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919)
    at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:835)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1396)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1386)
    at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
    at org.apache.tomcat.util.threads.InlineExecutorService.execute(InlineExecutorService.java:75)
    at java.base/java.util.concurrent.AbstractExecutorService.submit(AbstractExecutorService.java:145)
    at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:919)
    at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:265)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardService.startInternal(StandardService.java:432)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:930)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
    at org.apache.catalina.startup.Catalina.start(Catalina.java:772)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    at java.base/java.lang.reflect.Method.invoke(Method.java:577)
    at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:345)
    at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:476)
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'hibernateCustomerDAO': Unsatisfied dependency expressed through field 'sessionFactory'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.hibernate5.LocalSessionFactoryBean]: Factory method 'sessionFactory' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:639)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:119)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:399)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1431)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:619)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1391)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1311)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656)
    ... 48 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sessionFactory' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.hibernate5.LocalSessionFactoryBean]: Factory method 'sessionFactory' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:486)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208)
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:276)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1391)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1311)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:656)
    ... 62 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.hibernate5.LocalSessionFactoryBean]: Factory method 'sessionFactory' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653)
    ... 75 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in com.mc_es.spring.config.AppConfig: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NumberFormatException: Cannot parse null string
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:486)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542)
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335)
    at

Solution

The error must be caused due to these 2 lines of your dataSource method

dataSource.setMaxPoolSize(getIntProperty("connection.pool.maxSize"));
dataSource.setMaxIdleTime(getIntProperty("connection.pool.maxIdTime"));

Please check your application.properties file again for the right string value to be sent to the getIntProperty method

connection.pool.maxPoolSize = 20
connection.pool.maxIdleTime = 3000

Since the string you are passing doesn't exist in your application.properties file its returning null value which then is giving the error "Cannot parse null string"

int intPropValue = Integer.parseInt(propValue);