NullPointerException in AbstractEarModule when generating module ID with unresolved artifact

## Description

In `AbstractEarModule.java:336-338`, a NullPointerException occurs if `generateId` is true but the artifact has not been resolved:

```java
if (generateId) {
Artifact theArtifact = getArtifact();
String generatedId = theArtifact.getType().toUpperCase() + "_" + theArtifact.getGroupId() + "."
+ theArtifact.getArtifactId();
```

`getArtifact()` is documented in the `EarModule` interface as returning `null` until the artifact is resolved. If a module's artifact is not yet resolved when `generateId` is true, `.getType()` throws an NPE.

## Expected behavior

Add a null check before generating the ID:

```java
if (generateId) {
Artifact theArtifact = getArtifact();
if (theArtifact == null) {
return;
}
...
}
```

Start with AbstractEarModule.java:336-338 and the EarModule interface documentation for getArtifact(). Exercise the generateId path with an unresolved artifact and verify that it no longer throws a NullPointerException while resolved artifacts still receive their generated IDs.

Written by the indexing model from the issue text.