handle null cluster in isAllowReplicasBelowDynClusterSizeFor (#1630)

Author: alai8

operator/src/main/java/oracle/kubernetes/weblogic/domain/model/DomainSpec.java

@@ -29,6 +29,8 @@
 import org.apache.commons.lang3.builder.HashCodeBuilder;
 import org.apache.commons.lang3.builder.ToStringBuilder;
 
+import static oracle.kubernetes.operator.KubernetesConstants.DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE;
+
 /** DomainSpec is a description of a domain. */
 @Description("DomainSpec is a description of a domain.")
 public class DomainSpec extends BaseConfiguration {
@@ -843,7 +845,8 @@ private boolean hasMaxUnavailable(Cluster cluster) {
   }
 
   private boolean isAllowReplicasBelowDynClusterSizeFor(Cluster cluster) {
-    return cluster.isAllowReplicasBelowMinDynClusterSize();
+    return cluster == null ? DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE :
+        cluster.isAllowReplicasBelowMinDynClusterSize();
   }
 
   public AdminServer getAdminServer() {

operator/src/test/java/oracle/kubernetes/weblogic/domain/DomainTestBase.java

@@ -334,6 +334,12 @@ public void whenNotSpecified_allowReplicasBelowMinDynamicClusterSizeHasDefault()
         equalTo(DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE));
   }
 
+  @Test
+  public void whenNoClusterSpec_allowReplicasBelowMinDynamicClusterSizeHasDefault() {
+    assertThat(domain.isAllowReplicasBelowMinDynClusterSize("cluster-with-no-spec"),
+        equalTo(DEFAULT_ALLOW_REPLICAS_BELOW_MIN_DYN_CLUSTER_SIZE));
+  }
+
   @Test
   public void whenBothClusterAndServerStateSpecified_managedServerUsesServerState() {
     configureServer(SERVER1).withDesiredState("STAND-BY");