[HUDI-1193](Upgrade http dependency version) (#1970)

diff --git a/pom.xml b/pom.xml
index 4ea922e..2c786cf 100644
--- a/pom.xml
+++ b/pom.xml
@@ -98,6 +98,7 @@
     <hive.exec.classifier>core</hive.exec.classifier>
     <metrics.version>4.1.1</metrics.version>
     <prometheus.version>0.8.0</prometheus.version>
+    <http.version>4.4.1</http.version>
     <spark.version>2.4.4</spark.version>
     <avro.version>1.8.2</avro.version>
     <scala.version>2.11.12</scala.version>
@@ -568,17 +569,17 @@
       <dependency>
         <groupId>org.apache.httpcomponents</groupId>
         <artifactId>fluent-hc</artifactId>
-        <version>4.3.2</version>
+        <version>${http.version}</version>
       </dependency>
       <dependency>
         <groupId>org.apache.httpcomponents</groupId>
         <artifactId>httpcore</artifactId>
-        <version>4.3.2</version>
+        <version>${http.version}</version>
       </dependency>
       <dependency>
         <groupId>org.apache.httpcomponents</groupId>
         <artifactId>httpclient</artifactId>
-        <version>4.3.6</version>
+        <version>${http.version}</version>
       </dependency>
 
       <!-- Jackson -->