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