Skip importing missing versions

- Modify URI_REGISTRY migration so that now we just log
  a warning if version cannot be calculated using a same way
  dataflow already expects during a deployment. As in this
  case version in a data item is left empty, only use
  those items where version is defined.
- Fixes #2933

Author: jvalkeal

spring-cloud-dataflow-server-core/src/main/java/org/springframework/cloud/dataflow/server/db/migration/AbstractMigrateUriRegistrySqlCommand.java

@@ -16,12 +16,12 @@
 package org.springframework.cloud.dataflow.server.db.migration;
 
 import java.sql.Connection;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -31,6 +31,7 @@
 import org.springframework.cloud.deployer.resource.maven.MavenProperties;
 import org.springframework.cloud.deployer.resource.support.DelegatingResourceLoader;
 import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.util.ObjectUtils;
 
 /**
  * Base implementation for a {@link SqlCommand} copying data from
@@ -122,7 +123,12 @@ protected List<AppRegistrationMigrationData> createAppRegistrationMigrationData(
 					armd.setName(split[1]);
 					armd.setType(ApplicationType.valueOf(split[0]).ordinal());
 					armd.setUri(uri);
-					armd.setVersion(arc.getResourceVersion(arc.getResource(uri)));
+					try {
+						armd.setVersion(arc.getResourceVersion(arc.getResource(uri)));
+					}
+					catch (Exception e) {
+						logger.warn("Skipping URI_REGISTRY item {} migration with URI {} due to lack of version number in the URI", name, uri, e);
+					}
 				}
 				else {
 					// we got *.*.metadata first
@@ -135,8 +141,8 @@ protected List<AppRegistrationMigrationData> createAppRegistrationMigrationData(
 				data.put(key, armd);
 			}
 		});
-
-		return new ArrayList<>(data.values());
+		// if we skipper version errors, filter those out
+		return data.values().stream().filter(i -> !ObjectUtils.isEmpty(i.getVersion())).collect(Collectors.toList());
 	}
 
 	/**