Bug 145991 [Regression]Invalid data set should not be allowed to drag or "Insert in layout"
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/DataSetHandle.java
CachedMetaData value = (CachedMetaData) propHandle.getValue( );
		if ( value == null )
			return null;
		return (CachedMetaDataHandle) value.getHandle( propHandle );
	}
	/**
	 * Set the value for the cached data set information.
	 * 
	 * @param metadata
	 *            a structure value include output column information ,
	 *            input/output parameter definitions.
	 * @return <code>CachedMetaDataHandle</code> to the input
	 *         <code>metadata</code>, return <code>null</code> if
	 *         <code>metadata</code> is <code>null</code>.
	 * @throws SemanticException
	 *             the input data is not valid.
	 */
	public CachedMetaDataHandle setCachedMetaData( CachedMetaData metadata )
			throws SemanticException
	{
		setProperty( SimpleDataSet.CACHED_METADATA_PROP, metadata );
		if ( metadata == null )
			return null;
		return (CachedMetaDataHandle) metadata
				.getHandle( getPropertyHandle( SimpleDataSet.CACHED_METADATA_PROP ) );
	}
	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.birt.report.model.api.DesignElementHandle#getPropertyHandle(java.lang.String)