fix default argument handling in rake artifact task (#13904)

Ruby allows methods to have default values in arguments if they're not
passed. However if a nil is passed then the default value isn't used.

The artifact:archives tasks were passing nil values to the exclusion
argument, causing all files to be included in the package.

This commit cleans the naming of the path lists and ensures the default
exclusion list is always used.

rakelib/artifacts.rake

@@ -73,7 +73,7 @@ namespace "artifact" do
     ]
   end
 
-  def exclude_paths
+  def default_exclude_paths
     return @exclude_paths if @exclude_paths
 
     @exclude_paths = []
@@ -91,24 +91,19 @@ namespace "artifact" do
     @exclude_paths
   end
 
-  def excludes
-    return @excludes if @excludes
-    @excludes = exclude_paths
-  end
-
-  def oss_excludes
+  def oss_exclude_paths
     return @oss_excludes if @oss_excludes
-    @oss_excludes = excludes + [ "x-pack/**/*" ]
+    @oss_excludes = default_exclude_paths + [ "x-pack/**/*" ]
   end
 
-  def files(excl=excludes)
-    Rake::FileList.new(*package_files).exclude(*excl)
+  def files(exclude_paths=default_exclude_paths)
+    Rake::FileList.new(*package_files).exclude(*exclude_paths)
   end
 
-  def source_modified_since?(time, excluder=nil)
+  def source_modified_since?(time, exclude_paths=default_exclude_paths)
     skip_list = ["logstash-core-plugin-api/versions-gem-copy.yml", "logstash-core/versions-gem-copy.yml"]
     result = false
-    files(excluder).each do |file|
+    files(exclude_paths).each do |file|
       next if File.mtime(file) < time || skip_list.include?(file)
       puts "file modified #{file}"
       result = true
@@ -165,7 +160,7 @@ namespace "artifact" do
   desc "Build all (jdk bundled and not) OSS tar.gz and zip of default logstash plugins with all dependencies"
   task "archives_oss" => ["prepare", "generate_build_metadata"] do
     #with bundled JDKs
-    license_details = ['APACHE-LICENSE-2.0',"-oss", oss_excludes]
+    license_details = ['APACHE-LICENSE-2.0',"-oss", oss_exclude_paths]
     create_archive_pack(license_details, "x86_64", "linux", "windows", "darwin")
     create_archive_pack(license_details, "arm64", "linux")
 
@@ -407,7 +402,7 @@ namespace "artifact" do
   end
 
 
-  def build_tar(license, tar_suffix = nil, excluder=nil, platform: '')
+  def build_tar(license, tar_suffix = nil, exclude_paths=default_exclude_paths, platform: '')
     require "zlib"
     require 'rubygems'
     require 'rubygems/package'
@@ -420,7 +415,7 @@ namespace "artifact" do
     puts("[artifact:tar] building #{tarpath}")
     gz = Zlib::GzipWriter.new(File.new(tarpath, "wb"), Zlib::BEST_COMPRESSION)
     Gem::Package::TarWriter.new(gz) do |tar|
-      files(excluder).each do |path|
+      files(exclude_paths).each do |path|
         write_to_tar(tar, path, "logstash-#{LOGSTASH_VERSION}#{PACKAGE_SUFFIX}/#{path}")
       end
 
@@ -457,14 +452,14 @@ namespace "artifact" do
     end
   end
 
-  def build_zip(license, zip_suffix = "", excluder=nil, platform: '')
+  def build_zip(license, zip_suffix = "", exclude_paths=default_exclude_paths, platform: '')
     require 'zip'
     ensure_logstash_version_constant_defined
     zippath = "build/logstash#{zip_suffix}-#{LOGSTASH_VERSION}#{PACKAGE_SUFFIX}#{platform}.zip"
     puts("[artifact:zip] building #{zippath}")
     File.unlink(zippath) if File.exists?(zippath)
     Zip::File.open(zippath, Zip::File::CREATE) do |zipfile|
-      files(excluder).each do |path|
+      files(exclude_paths).each do |path|
         path_in_zip = "logstash-#{LOGSTASH_VERSION}#{PACKAGE_SUFFIX}/#{path}"
         zipfile.add(path_in_zip, path)
       end
@@ -507,13 +502,14 @@ namespace "artifact" do
 
 
     suffix = ""
-    excluder = nil
     if oss
       suffix= "-oss"
-      excludes = oss_excludes
+      exclude_paths = oss_exclude_paths
+    else
+      exclude_paths = default_exclude_paths
     end
 
-    files(excludes).each do |path|
+    files(exclude_paths).each do |path|
       next if File.directory?(path)
       # Omit any config dir from /usr/share/logstash for packages, since we're
       # using /etc/logstash below