Fix Checksum algo spec to pass JRuby CI (#2858)

* Update `checksum_algorithm` plugin to use IO.copy_stream for JRuby

---------

Co-authored-by: Juli Tera <[email protected]>
Co-authored-by: Matt Muller <[email protected]>

Author: jterapin

gems/aws-sdk-core/CHANGELOG.md

@@ -1,6 +1,8 @@
 Unreleased Changes
 ------------------
 
+* Issue - Updated `checksum_algorithm` plugin to use IO.copy_stream for JRuby.
+
 3.173.0 (2023-05-18)
 ------------------
 

gems/aws-sdk-core/lib/aws-sdk-core/plugins/checksum_algorithm.rb

@@ -314,7 +314,7 @@ def rewind
           @io.rewind
         end
 
-        def read(length, buf)
+        def read(length, buf = nil)
           # account for possible leftover bytes at the end, if we have trailer bytes, send them
           if @trailer_io
             return @trailer_io.read(length, buf)

gems/aws-sdk-core/spec/aws/plugins/checksum_algorithm_spec.rb

@@ -181,12 +181,8 @@ module Plugins
             expect(headers['x-amz-decoded-content-length']).to eq('11')
             # capture the body by reading it into a new IO object
             body = StringIO.new
-            if (defined?(JRUBY_VERSION))
-              body <<  context.http_request.body.read(1000, String.new) + context.http_request.body.read(1000, String.new)
-            else
-              # IO.copy_stream is the same method used by Net::Http to write our body to the socket
-              IO.copy_stream(context.http_request.body, body)
-            end
+            # IO.copy_stream is the same method used by Net::Http to write our body to the socket
+            IO.copy_stream(context.http_request.body, body)
             body.rewind
             expect(body.read).to eq "b\r\nHello World\r\n0\r\nx-amz-checksum-sha256:pZGm1Av0IEBKARczz7exkNYsZb8LzaMrV7J32a2fFG4=\r\n\r\n"
           end)
@@ -195,11 +191,11 @@ module Plugins
         end
 
         it 'handles header-based auth with checksum in header' do
-            client.stub_responses(:some_operation, -> (context) do
-              expect(context.http_request.headers['x-amz-checksum-sha256']).to eq('pZGm1Av0IEBKARczz7exkNYsZb8LzaMrV7J32a2fFG4=')
-              expect(context.http_request.body.read).to eq('Hello World')
-            end)
-            client.some_operation(checksum_algorithm: 'sha256', body: 'Hello World')
+          client.stub_responses(:some_operation, -> (context) do
+            expect(context.http_request.headers['x-amz-checksum-sha256']).to eq('pZGm1Av0IEBKARczz7exkNYsZb8LzaMrV7J32a2fFG4=')
+            expect(context.http_request.body.read).to eq('Hello World')
+          end)
+          client.some_operation(checksum_algorithm: 'sha256', body: 'Hello World')
         end
 
         it 'handles sigv4-streaming auth with checksum in trailer' do