NIFI-14738 Updated version to 2.2.0

pom.xml

diff --git a/pom.xml b/pom.xml
index fe65061..b8b554a 100644
--- a/pom.xml
+++ b/pom.xml
@@ -10,7 +10,7 @@
 
     <groupId>org.apache.nifi</groupId>
     <artifactId>nifi-api</artifactId>
-    <version>2.2.0-SNAPSHOT</version>
+    <version>2.2.0</version>
     <packaging>jar</packaging>
 
     <name>nifi-api</name>