Improve object creation and conversion between lists and arrays

Author: jpfennelly

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsHttpApiV2ProxyHttpServletRequest.java

@@ -298,8 +298,16 @@ public Enumeration<String> getParameterNames() {
     @Override
     @SuppressFBWarnings("PZLA_PREFER_ZERO_LENGTH_ARRAYS") // suppressing this as according to the specs we should be returning null here if we can't find params
     public String[] getParameterValues(String s) {
-        List<String> values = new ArrayList<>(Arrays.asList(getQueryParamValues(queryString, s, config.isQueryStringCaseSensitive())));
 
+        List<String> values = getQueryParamValuesAsList(queryString, s, config.isQueryStringCaseSensitive());
+
+        // copy list so we don't modifying the underlying multi-value query params
+        if (values != null) {
+            values = new ArrayList<>(values);
+        } else {
+            values = new ArrayList<>();
+        }
+        
         values.addAll(Arrays.asList(getFormBodyParameterCaseInsensitive(s)));
 
         if (values.size() == 0) {

aws-serverless-java-container-core/src/main/java/com/amazonaws/serverless/proxy/internal/servlet/AwsProxyHttpServletRequest.java

@@ -370,15 +370,16 @@ public Enumeration<String> getParameterNames() {
     @SuppressFBWarnings("PZLA_PREFER_ZERO_LENGTH_ARRAYS") // suppressing this as according to the specs we should be returning null here if we can't find params
     public String[] getParameterValues(String s) {
 
-    // TODO lots of back and forth arrays and lists here, sort it out!
-        List<String> values = new ArrayList<>(Arrays.asList(getQueryParamValues(request.getMultiValueQueryStringParameters(), s, config.isQueryStringCaseSensitive())));
-        // List<String> values = getQueryParamValuesAsList(request.getMultiValueQueryStringParameters(), s, config.isQueryStringCaseSensitive());
         // decode key if ALB
         if (request.getRequestSource() == RequestSource.ALB) {
             s = decodeValueIfEncoded(s);
         }
 
+        List<String> values = getQueryParamValuesAsList(request.getMultiValueQueryStringParameters(), s, config.isQueryStringCaseSensitive());
 
+        // copy list so we don't modifying the underlying multi-value query params
+        values = values != null ? new ArrayList<>(values) : new ArrayList<>();
+
         // decode values if ALB
         if (values != null && request.getRequestSource() == RequestSource.ALB) {
             values = values.stream().map(AwsHttpServletRequest::decodeValueIfEncoded).collect(Collectors.toList());