Return the last instance of u=.

As per RFC8941: <https://www.rfc-editor.org/rfc/rfc8941#section-3.2>.

lib/protocol/http/header/priority.rb

@@ -29,13 +29,15 @@ def << value
 				# The default urgency level if not specified.
 				DEFAULT_URGENCY = 3
 
-				# Returns the urgency level if specified. 0 is the highest priority, and 7 is the lowest.
+				# The urgency level, if specified using `u=`. 0 is the highest priority, and 7 is the lowest.
+				#
+				# Note that when duplicate Dictionary keys are encountered, all but the last instance are ignored.
 				#
 				# @returns [Integer | Nil] the urgency level if specified, or `nil` if not present.
 				def urgency(default = DEFAULT_URGENCY)
-					if value = self.find { |value| value.start_with?("u=") }
+					if value = self.reverse_find{|value| value.start_with?("u=")}
 						_, level = value.split("=", 2)
-						return level.to_i
+						return Integer(level)
 					end
 
 					return default

lib/protocol/http/header/split.rb

@@ -39,6 +39,16 @@ def << value
 				def to_s
 					join(",")
 				end
+
+				protected
+
+				def reverse_find(&block)
+					reverse_each do |value|
+						return value if block.call(value)
+					end
+
+					return nil
+				end
 			end
 		end
 	end

test/protocol/http/header/priority.rb

@@ -55,10 +55,9 @@
 	end
 
 	with "u=2, u=5" do
-		it "prioritizes the first urgency directive" do
+		it "prioritizes the last urgency directive" do
 			expect(header).to have_attributes(
-				# First occurrence takes precedence
-				urgency: be == 2,
+				urgency: be == 5,
 			)
 		end
 	end