isNullable on ResultSetMetaData from DatabaseMetaData.getBestRowIdentifier values are opposite when there is no rows in ResultSet vs. when there is a row.

With code like the following:

DatabaseMetaData dmd = conn.getMetaData();
ResultSet rs = dmd.getBestRowIdentifier(null,"APP","a",3,true);
ResultSetMetaData rsmd = rs.getMetaData();
int actualCols = rsmd.getColumnCount();
for (int i = 0; i < actualCols; i++)

{ System.out.print("getColumnName: " + rsmd.getColumnName(i+1) + ", isNullable: "); System.out.println(rsmd.isNullable(i+1)); }

The printed values for isNullable returned are opposite of what they are when the getBestRowIdentifier call looks like this:
ResultSet rs = dmd.getBestRowIdentifier(null,"APP","a",1,true);

In the latter case, the values are:
getColumnName: SCOPE, isNullable: 0
getColumnName: COLUMN_NAME, isNullable: 1
getColumnName: DATA_TYPE, isNullable: 0
getColumnName: TYPE_NAME, isNullable: 1
getColumnName: COLUMN_SIZE, isNullable: 0
getColumnName: BUFFER_LENGTH, isNullable: 0
getColumnName: DECIMAL_DIGITS, isNullable: 0
getColumnName: PSEUDO_COLUMN, isNullable: 0

In the first case, the values are:
getColumnName: SCOPE, isNullable: 1
getColumnName: COLUMN_NAME, isNullable: 0
getColumnName: DATA_TYPE, isNullable: 1
getColumnName: TYPE_NAME, isNullable: 1
getColumnName: COLUMN_SIZE, isNullable: 1
getColumnName: BUFFER_LENGTH, isNullable: 1
getColumnName: DECIMAL_DIGITS, isNullable: 1
getColumnName: PSEUDO_COLUMN, isNullable: 1

The isNullable value should be stable.
It's probably worthwhile verifying what the value should be in the first place.