@Override
    protected void generateDeclarativeSection(StringBuilder source, ShaderNode shaderNode, String nodeSource, ShaderGenerationInfo info) {
        if (nodeSource.replaceAll("\\n", "").trim().length() > 0) {
            nodeSource = updateDefinesName(nodeSource, shaderNode);
            source.append("\n");
            unIndent();
            startCondition(shaderNode.getCondition(), source);
            source.append(nodeSource);
            source.append("\n");
            endCondition(shaderNode.getCondition(), source);
            indent();
        }
    }
{@inheritDoc}

if the declaration contains no code nothing is done, else it's appended
jme3-core/src/main/java/com/jme3/shader/Glsl100ShaderGenerator.java