Bug 126390 IDataSetInstance needs method to return column information
There is no way to get the Java equivalent of the JavaScript columnDefns array, which describes the columns in a data set.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/script/instance/IDataSetInstance.java
* Sets the query text of the data set.
	 * 
	 * @return The static query text for execution.
	 */
	void setQueryText( String queryText ) throws ScriptException;
	/**
	 * Get the value of a data set extension property. 
	 * 
	 * @param name Name of property; must not be null or empty
	 * @return Property value; null if property has not been defined 
	 */
	String getExtensionProperty( String name );
	/**
	 * Set the value of an extension property 
	 * 
	 * @param name Name of property; must not be null or empty
	 * @param value Property value; may be null
	 */
	void setExtensionProperty( String name, String value );
	
	/**
	 * Gets the data set extension properties, in the form of a ( name [String], value [String] )
	 * map. 
	 * 
	 * @return Extension properties as a Map of String->String pairs. Null if no extension
	 * property is defined
	 */
	Map getAllExtensionProperties( );
}