pass on SonaType username and password when testing examples

... since we don't have these properties within a gradle properties file during release build on CI.

Signed-off-by: Peter Gafert <peter.gafert@tngtech.com>

build-steps/release/check-uploaded-artifacts.gradle

@@ -173,7 +173,7 @@ task testRelease() {
         def outputStream = new ByteArrayOutputStream()
         exec {
             workingDir testReleaseDir
-            commandLine './gradlew', ":${exampleProjectName}:build"
+            commandLine './gradlew', ":${exampleProjectName}:build", '-P', "sonatypeUsername=${project.getProperty('sonatypeUsername')}", '-P', "sonatypePassword=${project.getProperty('sonatypePassword')}"
             ignoreExitValue true
             standardOutput = outputStream
         }