Update Apache httpclient to 4.5.2 and httpcore to 4.4.6

CQ: 15051
CQ: 15052
Change-Id: I532cd73253601ce1d2926850af2519aae6744a9c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

pom.xml

diff --git a/pom.xml b/pom.xml
index 4b7b37c..afa68a6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -206,7 +206,8 @@
     <servlet-api-version>3.1.0</servlet-api-version>
     <jetty-version>9.4.8.v20171121</jetty-version>
     <japicmp-version>0.10.0</japicmp-version>
-    <httpclient-version>4.3.6</httpclient-version>
+    <httpclient-version>4.5.2</httpclient-version>
+    <httpcore-version>4.4.6</httpcore-version>
     <slf4j-version>1.7.2</slf4j-version>
     <log4j-version>1.2.15</log4j-version>
     <maven-javadoc-plugin-version>2.10.4</maven-javadoc-plugin-version>
@@ -655,6 +656,12 @@
       </dependency>
 
       <dependency>
+        <groupId>org.apache.httpcomponents</groupId>
+        <artifactId>httpcore</artifactId>
+        <version>${httpcore-version}</version>
+      </dependency>
+
+      <dependency>
         <groupId>org.slf4j</groupId>
         <artifactId>slf4j-api</artifactId>
         <version>${slf4j-version}</version>