Correct usage of TypeTokens

Author: chadlwilson

src/main/java/com.tw.go.config.json/JSONUtils.java

@@ -1,15 +1,21 @@
 package com.tw.go.config.json;
 
 
+import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.reflect.TypeToken;
 
+import java.util.Map;
+
 class JSONUtils {
-    static <T> T fromJSON(String json) {
-        return new GsonBuilder().create().fromJson(json, new TypeToken<T>() {}.getType());
+
+    private static final Gson GSON = new GsonBuilder().create();
+
+    static Map<String, String> fromJSON(String json) {
+        return GSON.fromJson(json, new TypeToken<Map<String, String>>() {}.getType());
     }
 
     static String toJSON(Object object) {
-        return new GsonBuilder().create().toJson(object);
+        return GSON.toJson(object);
     }
 }

src/main/java/com.tw.go.config.json/JsonConfigPlugin.java

@@ -158,7 +158,7 @@ private GoPluginApiResponse handleParseContentRequest(GoPluginApiRequest request
         return handlingErrors(() -> {
             ParsedRequest parsed = ParsedRequest.parse(request);
             FilenameMatcher matcher = new FilenameMatcher(getPipelinePattern(parsed), getEnvironmentPattern(parsed));
-            Map<String, String> contents = parsed.getParam("contents");
+            Map<String, String> contents = parsed.getParam("contents", String.class);
 
             JsonConfigCollection result = new JsonConfigCollection();
             contents.forEach((filename, content) -> {
@@ -190,7 +190,7 @@ private GoPluginApiResponse handlePipelineExportRequest(GoPluginApiRequest reque
         return handlingErrors(() -> {
             ParsedRequest parsed = ParsedRequest.parse(request);
 
-            Map<String, Object> pipeline = parsed.getParam("pipeline");
+            Map<String, Object> pipeline = parsed.getParam("pipeline", Object.class);
             String name = (String) pipeline.get("name");
 
             DefaultGoPluginApiResponse response = success(gson.toJson(Collections.singletonMap("pipeline", prettyPrint.toJson(pipeline))));

src/main/java/com.tw.go.config.json/ParsedRequest.java

@@ -5,6 +5,8 @@
 import com.google.gson.reflect.TypeToken;
 import com.thoughtworks.go.plugin.api.request.GoPluginApiRequest;
 
+import java.util.Map;
+
 import static java.lang.String.format;
 
 class ParsedRequest {
@@ -15,7 +17,6 @@ class ParsedRequest {
     private static final String PARAM_NOT_A_STRING_MESSAGE = "Expected `%s` param in request type `%s` to be a string";
     private static final String PARAM_FAILED_TO_PARSE_TO_TYPE = "Failed to parse parameter `%s` for request type `%s`: %s";
     private static final String PARAM_CONFIGURATIONS = "configurations";
-    private static final String INVALID_REPO_CONFIGURATION_KEY = "Config repo configuration has invalid key `%s`";
     private final String requestName;
     private final JsonObject params;
 
@@ -70,15 +71,15 @@ String getStringParam(String paramName) {
         }
     }
 
-    <T> T getParam(String paramName) {
+    <V> Map<String, V> getParam(String paramName, Class<V> valueClass) {
         try {
             JsonElement json = params.get(paramName);
 
             if (null == json || json.isJsonNull()) {
                 throw new RequestParseException(format(MISSING_PARAM_MESSAGE, paramName, requestName));
             }
 
-            return GSON.fromJson(json, new TypeToken<T>() {}.getType());
+            return GSON.fromJson(json, TypeToken.getParameterized(Map.class, String.class, valueClass).getType());
         } catch (Exception e) {
             throw new RequestParseException(format(PARAM_FAILED_TO_PARSE_TO_TYPE, paramName, requestName, e.getMessage()));
         }