@Override
    protected void generateVaryings(StringBuilder source, ShaderGenerationInfo info, ShaderType type) {
        source.append("\n");
        for (ShaderNodeVariable var : info.getVaryings()) {
            declareVarying(source, var, type != ShaderType.Vertex);
        }
    }
{@inheritDoc}

attributes are all declared, inPosition is declared even if it's not in
the list and its condition is nulled.
jme3-core/src/main/java/com/jme3/shader/Glsl100ShaderGenerator.java