Forces encoding of XML to UTF-8 prior to converting to JSON

Fixes #2894.

app/controllers/api_controller.rb

@@ -55,6 +55,15 @@ def show
         # escape double quotes (because they may appear in node values)
         xml = xml.gsub(%(\"), %(\\\"))
 
+        # Non-ASCII characters that are valid UTF-8 will throw an error during
+        # the translation process. Since we want UTF-8 in and out, forcing
+        # encoding to UTF-8 here should alleviate issues of where a multibyte
+        # char is not recognized. However, if non UTF-U encodings are being
+        # used, then this still may error, and we need to re-open the discussion
+        # about how/wehther to support other encodings, which would have to be
+        # stored/read within the PBCore documents themselves, i would think.
+        xml.force_encoding('UTF-8')
+
         json = pbcore_xml_to_json_xsl_doc.transform(Nokogiri::XML(xml))
         render json: JSON.pretty_generate(
           JSON.parse(json)