[FLINK-11304][docs][table] Fix typo in time attributes doc

This closes apache#7477.

docs/dev/table/streaming/time_attributes.md

@@ -264,7 +264,7 @@ Moreover, the `DataStream` returned by the `getDataStream()` method must have wa
 <div data-lang="java" markdown="1">
 {% highlight java %}
 // define a table source with a rowtime attribute
-public class UserActionSource implements StreamTableSource<Row>, DefinedRowtimeAttribute {
+public class UserActionSource implements StreamTableSource<Row>, DefinedRowtimeAttributes {
 
  @Override
  public TypeInformation<Row> getReturnType() {
@@ -284,9 +284,15 @@ public class UserActionSource implements StreamTableSource<Row>, DefinedRowtimeA
  }
 
  @Override
- public String getRowtimeAttribute() {
+ public List<RowtimeAttributeDescriptor> getRowtimeAttributeDescriptors() {
   // Mark the "UserActionTime" attribute as event-time attribute.
-  return "UserActionTime";
+  // We create one attribute descriptor of "UserActionTime".
+  RowtimeAttributeDescriptor rowtimeAttrDescr = new RowtimeAttributeDescriptor(
+  "UserActionTime",
+  new ExistingField("UserActionTime"),
+  new AscendingTimestamps());
+  List<RowtimeAttributeDescriptor> listRowtimeAttrDescr = Collections.singletonList(rowtimeAttrDescr);
+  return listRowtimeAttrDescr;
  }
 }
 
@@ -301,7 +307,7 @@ WindowedTable windowedTable = tEnv
 <div data-lang="scala" markdown="1">
 {% highlight scala %}
 // define a table source with a rowtime attribute
-class UserActionSource extends StreamTableSource[Row] with DefinedRowtimeAttribute {
+class UserActionSource extends StreamTableSource[Row] with DefinedRowtimeAttributes {
 
  override def getReturnType = {
   val names = Array[String]("Username" , "Data", "UserActionTime")
@@ -317,9 +323,15 @@ class UserActionSource extends StreamTableSource[Row] with DefinedRowtimeAttribu
   stream
  }
 
- override def getRowtimeAttribute = {
+ override def getRowtimeAttributeDescriptors: util.List[RowtimeAttributeDescriptor] = {
   // Mark the "UserActionTime" attribute as event-time attribute.
-  "UserActionTime"
+  // We create one attribute descriptor of "UserActionTime".
+  val rowtimeAttrDescr = new RowtimeAttributeDescriptor(
+  "UserActionTime",
+  new ExistingField("UserActionTime"),
+  new AscendingTimestamps)
+  val listRowtimeAttrDescr = Collections.singletonList(rowtimeAttrDescr)
+  listRowtimeAttrDescr
  }
 }