public void setLanguage(String language) {
            if (language == null) {
                throw new IllegalArgumentException("Shader language cannot be null");
            }
            this.language = language;
            setUpdateNeeded();
        }
Shader source describes a shader object in OpenGL. Each shader source
is assigned a certain pipeline which it controls (described by its type).
jme3-core/src/main/java/com/jme3/shader/Shader.java