This interfaces is implemented by tags that allow attributes to be set
externally to the tag. The HTML tags for example, allow certain attributes to
be set by children tags through the use of the attribute tag.
Set an attribute value on the implementing class. The name represents
the name of the attribute. The value represents the value and may contains
an expression. The facet is optional and may be used by complex types to
target the attribute to a sub part of the generated markup. This method may result in errors
being generated.
Parameters: name - The name of the attribute. This value may not be null or the empty string. Parameters: value - The value of the attribute. This may contain an expression. Parameters: facet - The name of a facet to which the attribute will be applied. This is optional. throws: JspException - A JspException may be thrown if there is an error setting the attribute.