chore: cherry picked API service

Author: reeshika-h

contentstack/build.gradle

@@ -139,13 +139,15 @@ android {
 }
 configurations { archives }
 dependencies {
+    androidTestImplementation 'org.junit.jupiter:junit-jupiter:5.8.1'
     def multidex = "2.0.1"
     def volley = "1.2.1"
     def junit = "4.13.2"
     configurations.configureEach { resolutionStrategy.force 'com.android.support:support-annotations:23.1.0' }
     implementation fileTree(include: ['*.jar'], dir: 'libs')
     implementation "com.android.volley:volley:$volley"
     implementation "junit:junit:$junit"
+
     // For AGP 7.4+
     coreLibraryDesugaring 'com.android.tools:desugar_jdk_libs:2.0.4'
     testImplementation 'junit:junit:4.13.2'

contentstack/src/main/java/com/contentstack/sdk/APIService.java

@@ -0,0 +1,23 @@
+package com.contentstack.sdk;
+
+import okhttp3.ResponseBody;
+import retrofit2.Call;
+import retrofit2.http.GET;
+import retrofit2.http.HeaderMap;
+import retrofit2.http.Query;
+import retrofit2.http.Url;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+
+public interface APIService {
+    @GET
+    Call<ResponseBody> getRequest(
+            @Url String url, @HeaderMap LinkedHashMap<String, Object> headers);
+
+    @GET("v3/taxonomies/entries")
+    Call<ResponseBody> getTaxonomy(
+            @HeaderMap Map<String, Object> headers,
+            @Query("query") String query);
+}

contentstack/src/main/java/com/contentstack/sdk/Stack.java

@@ -52,6 +52,7 @@ public class Stack implements INotifyClass {
     protected String limit = null;
     protected String localeCode;
     private SyncResultCallBack syncCallBack;
+    protected APIService service;
 
 
     protected Stack() {

contentstack/src/main/java/com/contentstack/sdk/TaxonomyCallback.java

@@ -0,0 +1,14 @@
+package com.contentstack.sdk;
+
+
+import org.json.JSONObject;
+
+public interface TaxonomyCallback {
+    /**
+     * This method is called wen API response gets received
+     * @param response the response of type JSON
+     * @param error the error of type @{@link Error}
+     */
+    void onResponse(JSONObject response, Error error);
+
+}