Issue #51 Simple Cache is not Thread Safe (and remove unused imports)

src/main/java/io/ipinfo/api/cache/Cache.java

@@ -1,8 +1,5 @@
 package io.ipinfo.api.cache;
 
-import io.ipinfo.api.model.ASNResponse;
-import io.ipinfo.api.model.IPResponse;
-
 public interface Cache {
     /**
      * Gets an arbitrary object stored in cache.

src/main/java/io/ipinfo/api/cache/SimpleCache.java

@@ -3,12 +3,12 @@
 import java.time.Duration;
 import java.time.Instant;
 import java.time.temporal.ChronoField;
-import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
 
 public class SimpleCache implements Cache {
     private final Duration duration;
-    private final Map<String, Payload> cache = new HashMap<>();
+    private final Map<String, Payload> cache = new ConcurrentHashMap<>();
 
     public SimpleCache(Duration duration) {
         this.duration = duration;

src/main/java/io/ipinfo/api/request/MapRequest.java

@@ -3,7 +3,10 @@
 import io.ipinfo.api.errors.ErrorResponseException;
 import io.ipinfo.api.errors.RateLimitedException;
 import io.ipinfo.api.model.MapResponse;
-import okhttp3.*;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
 
 import java.util.List;
 

src/test/java/io/ipinfo/IPinfoTest.java

@@ -1,14 +1,11 @@
 package io.ipinfo;
 
 import io.ipinfo.api.IPinfo;
-import io.ipinfo.api.errors.ErrorResponseException;
 import io.ipinfo.api.errors.RateLimitedException;
 import io.ipinfo.api.model.ASNResponse;
 import io.ipinfo.api.model.IPResponse;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import java.lang.reflect.Array;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;