It seems that after JDK-8214712 values of deprecated attributes
are now null which doesn't perfectly conform to the spec
https://download.java.net/java/early_access/jdk13/docs/api/java.base/java/util/jar/Attributes.Name.html

The following code
        System.out.println(Attributes.Name.EXTENSION_INSTALLATION);
        System.out.println(Attributes.Name.IMPLEMENTATION_URL);
        System.out.println(Attributes.Name.IMPLEMENTATION_VENDOR_ID);

on JDK13b13 shows
extensionInstallation = Extension-Installation
extensionInstallation = Implementation-URL
extensionInstallation = Implementation-Vendor-Id

on JDK13b14 shows
null
null
null

JDK-8214712 didn't change the spec and the currect state of the spec is confusing, for example:
================

    EXTENSION_INSTALLATION

    @Deprecated
    public static final Attributes.Name EXTENSION_INSTALLATION

    Deprecated.
    Extension mechanism is no longer supported.
    Name object for Extension-Installation manifest attribute.
================

As one can see - "Extension-Installation" value is still there. Same with other two deprecated properties.

The spec needs to be updated or the implementation should be corrected.