fixup! Handle null cases correctly to fix tests

Author: ascopes

maven-plugin-tools-annotations/src/main/java/org/apache/maven/tools/plugin/extractor/annotations/JavaAnnotationsMojoDescriptorExtractor.java

@@ -655,10 +655,6 @@ private void extendJavaProjectBuilder(
     }
 
     private boolean isExcludedDirectory(Collection<File> excludedDirectories, File sourceFile) {
-        if (excludedDirectories == null) {
-            return false;
-        }
-
         for (File excludedScanDirectory : excludedDirectories) {
             File candidateFile = sourceFile;
             while (candidateFile != null) {

maven-plugin-tools-api/src/main/java/org/apache/maven/tools/plugin/DefaultPluginToolsRequest.java

@@ -239,6 +239,9 @@ public String getUsedMavenApiVersion() {
 
     @Override
     public Collection<File> getExcludedScanDirectories() {
+        if (excludedScanDirectories == null) {
+            excludedScanDirectories = new HashSet<>();
+        }
         return excludedScanDirectories;
     }
 

maven-plugin-tools-java/src/main/java/org/apache/maven/tools/plugin/extractor/javadoc/JavaJavadocMojoDescriptorExtractor.java

@@ -581,10 +581,6 @@ protected void validate(MojoDescriptor mojoDescriptor) throws InvalidParameterEx
     }
 
     private boolean isExcludedDirectory(Collection<File> excludedDirectories, File sourceFile) {
-        if (excludedDirectories == null) {
-            return false;
-        }
-
         for (File excludedScanDirectory : excludedDirectories) {
             File candidateFile = sourceFile;
             while (candidateFile != null) {