FULL PRODUCT VERSION :
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
We have a webstart app. All our JARs are signed and we have set the following attributes in the manifest:

Permissions: all-permissions
Trusted-Only: true
Application-Library-Allowable-Codebase: *
Caller-Allowable-Codebase: *
Codebase: *

Since Java 7u45 there is no way to read our "META-INF/MANIFEST.MF" from our code.

  To make it work we *must* add the following attribute to the manifest:

Trusted-Library: true

The docu says "Trusted-Library" is only needed for webstart app which access/uses non signed stuff.

Again, we sign all our JARs!

REGRESSION. Last worked in version 7u45

ADDITIONAL REGRESSION INFORMATION:
java version "1.7.0_45"
Java(TM) SE Runtime Environment (build 1.7.0_45-b18)
Java HotSpot(TM) 64-Bit Server VM (build 24.45-b08, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a Webstart App, add a class "MyTest" with the follwing code:

    Enumeration<URL> resources = MyTest.class.getClassLoader().getResources("META-INF/MANIFEST.MF");
    while (resources.hasMoreElements()) {
        URL url = resources.nextElement();
        System.out.println(url.toString());
    }

call this code on startup, add following attributes to the manifest:

Permissions: all-permissions
Trusted-Only: true
Application-Library-Allowable-Codebase: *
Caller-Allowable-Codebase: *
Codebase: *

and sign the JAR. Start the webstart.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The META-INF/MANIFEST.MF of the signed webstart can be found/read.
ACTUAL -
The META-INF/MANIFEST.MF of the signed webstart can not be found/read.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
Add "Trusted-Library: true" to the manifest.