Replace bash expansion with tr (#9)

scripts/generate-sdk/generate-sdk.sh

@@ -105,24 +105,22 @@ for service_json in ${ROOT_DIR}/oas/*.json; do
     service="${service%.json}"
 
     # Remove invalid characters to ensure a valid Go pkg name
-    service="${service//-/}" # remove dashes
-    service="${service// /}" # remove empty spaces
-    service="${service//_/}" # remove underscores
-    service="${service,,}" # convert upper case letters to lower case
-    service=$(echo "${service}" | tr -d -c '[:alnum:]') # remove non-alphanumeric characters
+    service="${service//-/}"                                  # remove dashes
+    service="${service// /}"                                  # remove empty spaces
+    service="${service//_/}"                                  # remove underscores
+    service=$(echo "${service}" | tr '[:upper:]' '[:lower:]') # convert upper case letters to lower case
+    service=$(echo "${service}" | tr -d -c '[:alnum:]')       # remove non-alphanumeric characters
 
     go_pkg_name_format="^[a-z0-9]+$"
-    if [[ ! ${service} =~ ${go_pkg_name_format} ]]; # check that it is a single lower case word
-    then 
+    if [[ ! ${service} =~ ${go_pkg_name_format} ]]; then # check that it is a single lower case word
         echo "Service ${service} has an invalid Go package name even after removing invalid characters. The generate-sdk.sh script might need to be updated to catch corner case, contact the repo maintainers."
-        exit 1 
+        exit 1
     fi
 
     contains_empty_space_pattern=" |'"
-    if [[ ${service_json} =~ ${contains_empty_space_pattern} ]];
-    then
+    if [[ ${service_json} =~ ${contains_empty_space_pattern} ]]; then
         echo "OAS filename ${service_json} has empty spaces, the generation will fail. If the OAS was downloaded using the make download-oas command, it should be fixed in the api-specifications repo, please contact the repo maintainers at ${OAS_REPO}."
-        exit 1 
+        exit 1
     fi
 
     echo "Generating ${service} service..."