performance improvement

Author: Valentin Popov

src/main/java/com/microsoft/graph/authentication/TokenCredentialAuthProvider.java

@@ -5,6 +5,7 @@
 
 import java.net.URL;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
@@ -27,7 +28,7 @@ public class TokenCredentialAuthProvider extends BaseAuthenticationProvider {
      * @param tokenCredential Credential object inheriting the TokenCredential interface used to instantiate the Auth Provider
      */
     public TokenCredentialAuthProvider(@Nonnull final TokenCredential tokenCredential) {
-        this(Arrays.asList(DEFAULT_GRAPH_SCOPE), tokenCredential);
+        this(Collections.singletonList(DEFAULT_GRAPH_SCOPE), tokenCredential);
     }
 
     /**

src/main/java/com/microsoft/graph/core/Multipart.java

@@ -125,7 +125,7 @@ public static String createContentHeaderValue(@Nonnull final String contentValue
 
 		if(contentDispParameter != null) {
 			for(Map.Entry<String,String> entry : contentDispParameter.entrySet())
-				builder.append(";" + entry.getKey() + "=\"" + entry.getValue() + "\"");
+				builder.append(";").append(entry.getKey()).append("=\"").append(entry.getValue()).append("\"");
 		}
 		return builder.toString();
 	}
@@ -140,7 +140,7 @@ private String createPartHeader(Map<String, String> headers) {
 
         if(headers != null) {
             for(Map.Entry<String,String> entry : headers.entrySet())
-                builder.append(entry.getKey() +": "+entry.getValue() + RETURN);
+                builder.append(entry.getKey()).append(": ").append(entry.getValue()).append(RETURN);
             builder.append(RETURN);
         } else
             builder.append(defaultPartContent);

src/main/java/com/microsoft/graph/http/BaseRequest.java

@@ -228,7 +228,7 @@ private String addFunctionParameters() {
                 requestUrl.append("=");
                 if (option.getValue() != null) {
                     if (option.getValue() instanceof String) {
-                        requestUrl.append("'" + option.getValue() + "'");
+                        requestUrl.append("'").append(option.getValue()).append("'");
                     } else {
                         requestUrl.append(option.getValue());
                     }

src/main/java/com/microsoft/graph/httpcore/HttpClients.java

@@ -1,17 +1,15 @@
 package com.microsoft.graph.httpcore;
 
 import com.microsoft.graph.authentication.IAuthenticationProvider;
-
-import java.util.Arrays;
-import java.util.Objects;
-
-import javax.annotation.Nullable;
-import javax.annotation.Nonnull;
-
 import okhttp3.Interceptor;
 import okhttp3.OkHttpClient;
-import okhttp3.Protocol;
 import okhttp3.OkHttpClient.Builder;
+import okhttp3.Protocol;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Collections;
+import java.util.Objects;
 
 /**
  * Builder to get a custom HttpClient to be used for requests against Microsoft Graph
@@ -33,7 +31,7 @@ public static Builder custom() {
                     .addInterceptor(new TelemetryHandler())
                     .followRedirects(false)
                     .followSslRedirects(false)
-                    .protocols(Arrays.asList(Protocol.HTTP_1_1)); //https://stackoverflow.com/questions/62031298/sockettimeout-on-java-11-but-not-on-java-8
+                    .protocols(Collections.singletonList(Protocol.HTTP_1_1)); //https://stackoverflow.com/questions/62031298/sockettimeout-on-java-11-but-not-on-java-8
     }
 
     /**