Simplify qualifier comparison

Previously, the complexity of the qualifier comparison led to a single
method that was quite hard to understand.  This change simplifies that
method by breaking out smaller understandable and well-named chunks
with the same functionality.

[#50968083]

Author: nebhale

.yardopts

@@ -1,4 +1,5 @@
 --protected
+--no-private
 -
 LICENSE
 NOTICE

lib/java_buildpack/version_resolver.rb

@@ -52,11 +52,11 @@ def self.matches(tokenized_candidate_version, tokenized_version)
       end
     end
 
-    # Internal class. DO NOT USE.
+    # @private
     class TokenizedVersion < Array
       include Comparable
 
-      # Internal constant. DO NOT USE.
+      # @private
       WILDCARD = '+'
 
       def initialize(version, allow_wildcards = true)
@@ -70,25 +70,17 @@ def initialize(version, allow_wildcards = true)
         validate allow_wildcards
       end
 
-      # Internal method. DO NOT USE.
+      # @private
       def <=>(another)
         comparison = self[0] <=> another[0]
         comparison = self[1] <=> another[1] if comparison == 0
         comparison = self[2] <=> another[2] if comparison == 0
-
-        self_qualifier = self[3].nil? ? '' : self[3]
-        another_qualifier = another[3].nil? ? '' : another[3]
-        i = 0
-        until comparison != 0 || i == [self_qualifier.length, another_qualifier.length].min
-          comparison = char_compare(self_qualifier[i], another_qualifier[i])
-          i += 1
-        end
-        comparison = self_qualifier.length <=> another_qualifier.length  if comparison == 0
+        comparison = qualifier_compare(self[3].nil? ? '' : self[3], another[3].nil? ? '' : another[3]) if comparison == 0
 
         comparison
       end
 
-      # Internal method. DO NOT USE.
+      # @private
       def to_s
         @version
       end
@@ -132,6 +124,24 @@ def micro_and_qualifier(s)
         return micro, qualifier
       end
 
+      def minimum_qualifier_length(a, b)
+        [a.length, b.length].min
+      end
+
+      def qualifier_compare(a, b)
+        comparison = 0
+
+        i = 0
+        until comparison != 0 || i == minimum_qualifier_length(a, b)
+          comparison = char_compare(a[i], b[i])
+          i += 1
+        end
+
+        comparison = a.length <=> b.length  if comparison == 0
+
+        comparison
+      end
+
       def validate(allow_wildcards)
         post_wildcard = false
         self.each do |value|