Address reliance on default constructors in javax.sql

Summary

Replace a default constructor in javax.sql.rowset.RowSetMetaDataImpl with an equivalent explicit constructor.

Problem

The class javax.sql.rowset.RowSetMetaDataImpl relies on a default constructor.

Solution

Add an explicit public no-arg constructor.

Specification

diff -r b3af0bdfb85a src/java.sql.rowset/share/classes/javax/sql/rowset/RowSetMetaDataImpl.java
--- a/src/java.sql.rowset/share/classes/javax/sql/rowset/RowSetMetaDataImpl.java    Fri Jul 24 13:49:38 2020 -0700
+++ b/src/java.sql.rowset/share/classes/javax/sql/rowset/RowSetMetaDataImpl.java    Fri Jul 24 19:13:28 2020 -0700
@@ -52,6 +52,10 @@
  * @since 1.5
  */
 public class RowSetMetaDataImpl implements RowSetMetaData,  Serializable {
+    /**
+     * Constructs a {@code RowSetMetaDataImpl} object.
+     */
+    public RowSetMetaDataImpl() {}

     /**
      * The number of columns in the <code>RowSet</code> object that created