how to find some properties for Spring Boot

spring-boot-props

package org.springframework.boot.autoconfigure.orm.jpa;

import java.util.Map;

import javax.persistence.EntityManager;
import javax.sql.DataSource;

import org.hibernate.cfg.ImprovedNamingStrategy;
import org.hibernate.ejb.HibernateEntityManager;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.boot.autoconfigure.AutoConfigureAfter;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;
import org.springframework.boot.autoconfigure.jdbc.EmbeddedDatabaseConnection;
import org.springframework.boot.bind.RelaxedPropertyResolver;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.AbstractJpaVendorAdapter;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.annotation.EnableTransactionManagement;

/**
 * {@link EnableAutoConfiguration Auto-configuration} for Hibernate JPA.
 * 
 * @author Phillip Webb
 */
@Configuration
@ConditionalOnClass({ LocalContainerEntityManagerFactoryBean.class,
                EnableTransactionManagement.class, EntityManager.class,
                HibernateEntityManager.class })
@ConditionalOnBean(DataSource.class)
@EnableTransactionManagement
@AutoConfigureAfter(DataSourceAutoConfiguration.class)
public class HibernateJpaAutoConfiguration extends JpaBaseConfiguration implements
                BeanClassLoaderAware {

        private RelaxedPropertyResolver environment;

        private ClassLoader classLoader;

        public HibernateJpaAutoConfiguration() {
                this.environment = null;
        }

        @Override
        public void setBeanClassLoader(ClassLoader classLoader) {
                this.classLoader = classLoader;
        }

        @Override
        public void setEnvironment(Environment environment) {
                super.setEnvironment(environment);
                this.environment = new RelaxedPropertyResolver(environment,
                                "spring.jpa.hibernate.");
        }

        @Override
        protected AbstractJpaVendorAdapter createJpaVendorAdapter() {
                return new HibernateJpaVendorAdapter();
        }

        @Override
        protected void configure(
                        LocalContainerEntityManagerFactoryBean entityManagerFactoryBean) {
                Map<String, Object> properties = entityManagerFactoryBean.getJpaPropertyMap();
                properties.put("hibernate.ejb.naming_strategy", this.environment.getProperty(
                                "naming-strategy", ImprovedNamingStrategy.class.getName()));
                String ddlAuto = this.environment.getProperty("ddl-auto", getDefaultDdlAuto());
                if (!"none".equals(ddlAuto)) {
                        properties.put("hibernate.hbm2ddl.auto", ddlAuto);
                }
        }

        private String getDefaultDdlAuto() {
                EmbeddedDatabaseConnection embeddedDatabaseConnection = EmbeddedDatabaseConnection
                                .get(this.classLoader);
                if (embeddedDatabaseConnection == EmbeddedDatabaseConnection.NONE) {
                        return "none";
                }
                return "create-drop";
        }
}