activiti-engine-5.22.0-sources.jar
package org.activiti.engine.impl.cfg;
StandaloneInMemProcessEngineConfiguration
H2数据库的In Memory的流程引擎配置。
activiti-spring-5.22.0-sources.jar
package org.activiti.spring;
SpringProcessEngineConfiguration，
与Spring集成的流程引擎配置，当然可以用MYSQL了。