fix: add Javadoc for the main and infrastructure client distinction in HasKubernetesClient interface

Signed-off-by: xstefank <xstefank122@gmail.com>

Author: xstefank

operator-framework-junit5/src/main/java/io/javaoperatorsdk/operator/junit/HasKubernetesClient.java

@@ -3,7 +3,20 @@
 import io.fabric8.kubernetes.client.KubernetesClient;
 
 public interface HasKubernetesClient {
+  /**
+   * Returns the main Kubernetes client that is used to deploy the operator to the cluster.
+   *
+   * @return the main Kubernetes client
+   */
   KubernetesClient getKubernetesClient();
 
+  /**
+   * Returns the Kubernetes client that is used to deploy infrastructure resources to the cluster
+   * such as clusterroles, clusterrolebindings, etc. This client can be different from the main
+   * client in case you need to test the operator with a different restrictions more closely
+   * resembling the real restrictions it will have in production.
+   *
+   * @return the infrastructure Kubernetes client
+   */
   KubernetesClient getInfrastructureKubernetesClient();
 }