NPE in ManifestConfiguration.getClasspathPrefix() when prefix is set to null

[elharo]

Affected version: all

Description:

ManifestConfiguration.getClasspathPrefix() at line 248 calls .replaceAll() directly on the field without a null check:

public String getClasspathPrefix() {
    String cpp = classpathPrefix.replaceAll("\\\\", "/");
    if (cpp.length() != 0 && !cpp.endsWith("/")) {
        cpp += "/";
    }
    return cpp;
}

The field is initialized to "" at line 53, but the setter setClasspathPrefix(String) at line 220 stores the value as-is without a null guard:

public void setClasspathPrefix(String classpathPrefix) {
    this.classpathPrefix = classpathPrefix;
}

If any caller passes null to the setter, the getter throws NPE on null.replaceAll().

Impact: Callers passing null (e.g., from unset XML configuration elements mapped via Plexus) crash with NPE instead of getting the default empty prefix.