Eclipse: Error (Bytecode Outline) SOURCE FILE [in PROJECT] is not on its project's build path

JAR creation failed. See details for additional information.
  spring-core-4.1.4.RELEASE-sources/META-INF/MANIFEST.MF was replaced by the generated MANIFEST.MF and is no longer in the JAR.
  org/springframework/core/type/classreading [in spring-core-4.1.4.RELEASE-sources] is not on its project's build path
  Unable to get package fragment root: spring-core-4.1.4.RELEASE-sources/org/springframework/core/type/classreading/SimpleMetadataReader.java
    org/springframework/core/type/classreading [in spring-core-4.1.4.RELEASE-sources] is not on its project's build path

http://stackoverflow.com/questions/8194742/eclipse-error-bytecode-outline-source-file-in-project-is-not-on-its-project
I’ve just installer the ASM Eclipse Plugin (and restarted), which give an improved Bytecode Outline, and I can use it for the JRE classes, but looking at my own code, I get the error message in the title.
My java project is on Build Automatically, and I my source files do not have errors, and I can see the class files in the Default output folder defined in the Java Build Path of the Project’s properties.
Is it showing such a problem? “Error (Bytecode Outline) src/Foo.java [in BarProject] is not on its project’s build path. ” That’s a version problem. Use http://andrei.gmxhome.de/eclipse/as the update URL with the update manager and install the new version.