use kubeclient 4.4.latest; refactor tests for k8s api discovery

Update to kubeclient 4.4.latest - make dependency now on versions
between 4 and 5.  The new api makes a discovery call to
/api/v1 - I had to refactor the tests to take that into consideration.
I've tested this with fluentd with ocp 4.2 logging - tests pass.
I'm bumping the version to 2.3.0 from 2.2.x due to the big change
in the kubeclient version.  I also got rid of the dependency on
activesupport.

fluent-plugin-kubernetes_metadata_filter.gemspec

@@ -4,7 +4,7 @@ $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 
 Gem::Specification.new do |gem|
   gem.name          = "fluent-plugin-kubernetes_metadata_filter"
-  gem.version       = "2.2.0"
+  gem.version       = "2.3.0"
   gem.authors       = ["Jimmi Dyson"]
   gem.email         = ["[email protected]"]
   gem.description   = %q{Filter plugin to add Kubernetes metadata}
@@ -21,7 +21,7 @@ Gem::Specification.new do |gem|
 
   gem.add_runtime_dependency 'fluentd', ['>= 0.14.0', '< 2']
   gem.add_runtime_dependency "lru_redux"
-  gem.add_runtime_dependency "kubeclient", "~> 1.1.4"
+  gem.add_runtime_dependency "kubeclient", '< 5'
 
   gem.add_development_dependency "bundler", "~> 1.3"
   gem.add_development_dependency "rake"

lib/fluent/plugin/filter_kubernetes_metadata.rb

@@ -136,7 +136,7 @@ def fetch_namespace_metadata(namespace_name)
             metadata = parse_namespace_metadata(metadata)
             @stats.bump(:namespace_cache_api_updates)
             log.trace("parsed metadata for #{namespace_name}: #{metadata}") if log.trace?
-             @namespace_cache[metadata['namespace_id']] = metadata
+            @namespace_cache[metadata['namespace_id']] = metadata
             return metadata
           rescue Exception => e
             log.debug(e)
@@ -164,7 +164,6 @@ def log.trace?
       end
 
       require 'kubeclient'
-      require 'active_support/core_ext/object/blank'
       require 'lru_redux'
       @stats = KubernetesMetadata::Stats.new
 

lib/fluent/plugin/kubernetes_metadata_common.rb

@@ -111,3 +111,29 @@ def syms_to_strs(hsh)
 
   end
 end
+
+# copied from activesupport
+class Object
+  # An object is blank if it's false, empty, or a whitespace string.
+  # For example, +nil+, '', '   ', [], {}, and +false+ are all blank.
+  #
+  # This simplifies
+  #
+  #   !address || address.empty?
+  #
+  # to
+  #
+  #   address.blank?
+  #
+  # @return [true, false]
+  def blank?
+    respond_to?(:empty?) ? !!empty? : !self
+  end
+
+  # An object is present if it's not blank.
+  #
+  # @return [true, false]
+  def present?
+    !blank?
+  end
+end