final void notifyParamChanged(String paramName, VarType type, Object value) {
        Integer defineId = def.getShaderParamDefineId(paramName);

        if (defineId == null) {
            return;
        }

        paramDefines.set(defineId, type, value);
    }
Called by the material to tell the technique a parameter was modified.
Specify <code>null</code> for value if the param is to be cleared.
jme3-core/src/main/java/com/jme3/material/Technique.java