add verification and update docs

Author: whhe

docs/content/connectors/oceanbase-cdc.md

@@ -97,7 +97,7 @@ Connector Options
 The OceanBase CDC Connector contains some options for both sql and stream api as the following sheet. 
 
 *Note*: The connector supports two ways to specify the table list to listen to, and will get the union of the results when both way are used at the same time.
-1. Use `database-name` and `table-name` to match database and table names in regex. Can only be used in `initial` startup mode.
+1. Use `database-name` and `table-name` to match database and table names in regex. As the `obcdc` (former `liboblog`) only supports `fnmatch` now, we can't use regex directly to filter change events, so these two options can only be used in `initial` startup mode.
 2. Use `table-list` to match the exact value of database and table names.
 
 <div class="highlight">

flink-connector-oceanbase-cdc/src/main/java/com/ververica/cdc/connectors/oceanbase/OceanBaseSource.java

@@ -188,6 +188,17 @@ public SourceFunction<T> build() {
                             startupMode + " mode is not supported.");
             }
 
+            if (StringUtils.isNotEmpty(databaseName) || StringUtils.isNotEmpty(tableName)) {
+                if (StringUtils.isEmpty(databaseName) || StringUtils.isEmpty(tableName)) {
+                    throw new IllegalArgumentException(
+                            "'database-name' and 'table-name' should be configured at the same time");
+                }
+            } else {
+                checkNotNull(
+                        tableList,
+                        "'database-name', 'table-name' or 'table-list' should be configured");
+            }
+
             if (serverTimeZone == null) {
                 serverTimeZone = "UTC";
             }