Use empty component path list instead of null

Author: prdoyle

libs/entitlement/src/main/java/org/elasticsearch/entitlement/bootstrap/FilesEntitlementsValidation.java

@@ -17,6 +17,7 @@
 
 import java.nio.file.Path;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -44,7 +45,7 @@ static void validate(Map<String, Policy> pluginPolicies, PathLookup pathLookup)
                     .map(x -> ((FilesEntitlement) x))
                     .findFirst();
                 if (filesEntitlement.isPresent()) {
-                    var fileAccessTree = FileAccessTree.withoutExclusivePaths(filesEntitlement.get(), pathLookup, null);
+                    var fileAccessTree = FileAccessTree.withoutExclusivePaths(filesEntitlement.get(), pathLookup, List.of());
                     validateReadFilesEntitlements(pluginPolicy.getKey(), scope.moduleName(), fileAccessTree, readAccessForbidden);
                     validateWriteFilesEntitlements(pluginPolicy.getKey(), scope.moduleName(), fileAccessTree, writeAccessForbidden);
                 }

libs/entitlement/src/main/java/org/elasticsearch/entitlement/runtime/policy/PolicyManager.java

@@ -321,15 +321,16 @@ private ModuleEntitlements computeEntitlements(Class<?> requestingClass) {
                 );
             }
             case UNKNOWN -> {
-                return defaultEntitlements(UNKNOWN.componentName, null, moduleName);
+                return defaultEntitlements(UNKNOWN.componentName, List.of(), moduleName);
             }
             default -> {
                 assert policyScope.kind() == PLUGIN;
                 var pluginEntitlements = pluginsEntitlements.get(componentName);
+                Collection<Path> componentPaths = pluginSourcePaths.getOrDefault(componentName, List.of());
                 if (pluginEntitlements == null) {
-                    return defaultEntitlements(componentName, pluginSourcePaths.get(componentName), moduleName);
+                    return defaultEntitlements(componentName, componentPaths, moduleName);
                 } else {
-                    return getModuleScopeEntitlements(pluginEntitlements, moduleName, componentName, pluginSourcePaths.get(componentName));
+                    return getModuleScopeEntitlements(pluginEntitlements, moduleName, componentName, componentPaths);
                 }
             }
         }