Could not open ServletContext resource [/jdbc.properties] after switch to Java 1.8-Spring 4

Question

I have two Spring Projects, Backend and Frontend. The Upgrade of backend was trouble-free (Spring 4.1.2.RELEASE). While deploying the frontend i have this Exception:

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [acn.spring.config.AppConfig]; nested exception is java.io.FileNotFoundException: Could not open ServletContext resource [/jdbc.properties]
    at org.springframework.context.annotation.ConfigurationClassParser.processImports(ConfigurationClassParser.java:489)
....
Caused by: 
java.io.FileNotFoundException: Could not open ServletContext resource [/jdbc.properties]

This is the WebAppInitializer for Frontend:

@Configuration
public class WebAppInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class<?>[] { AppConfig.class };
    }
    .....

Appconfig is in backend project and looks like this:

@Import(DataConfig.class)
@Configuration
public class AppConfig {
   ...
}

The missing property file is used in DataConfig which is imported here:

@PropertySource("jdbc.properties")
@Configuration
public class DataConfig {
   ...
}

Why could not the property file not be found?

EDIT: Jar structure of the backend:

• META-INF
  • MANIFEST.MF
  • maven
• mySourcePackages Structure
• jdbc.properties

War structure of the frontend:

• META-INF
  • MANIFEST.MF
  • maven
• resources
• WEB-INF
  • classes
    • mySourcePackages Structure
  • jsp
  • lib
    • all the jars including backend.jar

Answer 1

Tell the configuration class that your properties is in the classpath. Otherwise, it will look in the Servlet context by default since it's a web context.

@PropertySource("classpath:jdbc.properties")

Answer 2

Check jdbc.properties is in the root of your classpath. If that's not the problem I'd need more details on your problem, like what's your folder structure and if you compile-package to a war.