upgrade GSON and slf4j-api version #651 (#663)

Signed-off-by: chandresh-pancholi <[email protected]>

Author: chandresh-pancholi

build.gradle

@@ -21,8 +21,8 @@ ext.opentracingVersion = getProperty('opentracingVersion','0.33.0')
 ext.guavaVersion = getProperty('guavaVersion','18.0')
 ext.apacheThriftVersion = getProperty('apacheThriftVersion','0.12.0')
 ext.jerseyVersion = getProperty('jerseyVersion','2.22.2')
-ext.slf4jVersion = getProperty('slf4jVersion','1.7.25')
-ext.gsonVersion = getProperty('gsonVersion','2.8.2')
+ext.slf4jVersion = getProperty('slf4jVersion','1.7.28')
+ext.gsonVersion = getProperty('gsonVersion','2.8.6')
 ext.tracerResolverVersion = getProperty('tracerResolverVersion','0.1.8')
 ext.micrometerVersion = getProperty('micrometerVersion','1.2.0')
 ext.okhttpVersion = getProperty('okhttpVersion','3.9.0')