fix: Make the LRU map synchronized to keep cache thread safe. (#380)

src/main/java/com/synopsys/integration/blackduck/http/client/cache/CacheableResponse.java

@@ -12,7 +12,6 @@
 import java.nio.charset.Charset;
 import java.util.Map;
 
-import org.apache.commons.collections4.map.LRUMap;
 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpUriRequest;
 
@@ -24,11 +23,11 @@
 public class CacheableResponse implements Response {
     private final Request request;
     private final Response response;
-    private final LRUMap<Request, Response> cache;
+    private final Map<Request, Response> cache;
 
     private String stringResponse;
 
-    public CacheableResponse(Request request, Response response, LRUMap<Request, Response> cache) {
+    public CacheableResponse(Request request, Response response, Map<Request, Response> cache) {
         this.request = request;
         this.response = response;
         this.cache = cache;

src/main/java/com/synopsys/integration/blackduck/http/client/cache/CachingHttpClient.java

@@ -7,6 +7,8 @@
  */
 package com.synopsys.integration.blackduck.http.client.cache;
 
+import java.util.Collections;
+import java.util.Map;
 import java.util.Optional;
 
 import org.apache.commons.collections4.map.LRUMap;
@@ -29,11 +31,11 @@
 
 public class CachingHttpClient implements BlackDuckHttpClient {
     private final BlackDuckHttpClient blackDuckHttpClient;
-    private final LRUMap<Request, Response> cache;
+    private final Map<Request, Response> cache;
 
     public CachingHttpClient(BlackDuckHttpClient blackDuckHttpClient) {
         this.blackDuckHttpClient = blackDuckHttpClient;
-        this.cache = new LRUMap<>(1000);
+        this.cache = Collections.synchronizedMap(new LRUMap<>(1000));
     }
 
     public void emptyCache() {