[maven-4.0.x] DefaultModelBuilder: NPE on null rootDirectory

[elharo]

DefaultModelBuilder: NPE on null rootDirectory

Found in: maven-4.0.x branch
File: impl/maven-impl/src/main/java/org/apache/maven/impl/model/DefaultModelBuilder.java (lines 719-720)
Severity: High

Description

rootDirectory can be null — it is assigned at lines 1544-1551 where both session.getRootDirectory() can throw and modelSource.getPath() can return null. But the getEnhancedProperties method calls .toString() on it without null check:

try {
    String root = rootDirectory.toString();
    String rootUri = rootDirectory.toUri().toString();
    ...
} catch (IllegalStateException e) {
    // Root directory not available, continue without it
}

A null rootDirectory throws NullPointerException, which is NOT caught by the catch(IllegalStateException) block. This can crash the build entirely for POMs with a modelSource that has no path and no session root directory.