Fix ConfigurationImpl- Add null test before using nullable values

Issue-ID: SDC-4402
Signed-off-by: shikha0203 <shivani.khare@est.tech>
Change-Id: I38efdeffadb4627e059e7827f15dc39de6b753cd
diff --git a/common/onap-common-configuration-management/onap-configuration-management-core/src/main/java/org/onap/config/impl/ConfigurationImpl.java b/common/onap-common-configuration-management/onap-configuration-management-core/src/main/java/org/onap/config/impl/ConfigurationImpl.java
index 964b8d1..46a4c43 100644
--- a/common/onap-common-configuration-management/onap-configuration-management-core/src/main/java/org/onap/config/impl/ConfigurationImpl.java
+++ b/common/onap-common-configuration-management/onap-configuration-management-core/src/main/java/org/onap/config/impl/ConfigurationImpl.java
@@ -35,6 +35,7 @@
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
+
 import org.apache.commons.configuration2.ex.ConfigurationException;
 import org.onap.config.ConfigurationUtils;
 import org.onap.config.Constants;
@@ -204,8 +205,8 @@
                 namespace = tenantNamespaceArray[1];
             }
         }
-        tenant = ConfigurationRepository.lookup().isValidTenant(tenant) ? tenant.toUpperCase() : Constants.DEFAULT_TENANT;
-        namespace = ConfigurationRepository.lookup().isValidNamespace(namespace) ? namespace.toUpperCase() : Constants.DEFAULT_NAMESPACE;
+        tenant = tenant != null && ConfigurationRepository.lookup().isValidTenant(tenant) ? tenant.toUpperCase() : Constants.DEFAULT_TENANT;
+        namespace = namespace != null && ConfigurationRepository.lookup().isValidNamespace(namespace) ? namespace.toUpperCase() : Constants.DEFAULT_NAMESPACE;
         hints = hints == null || hints.length == 0 ? new Hint[]{Hint.EXTERNAL_LOOKUP, Hint.NODE_SPECIFIC} : hints;
         T returnValue;
         returnValue = getInternal(tenant, namespace, key, clazz, hints);