Dump all PlantUML skinparams to standard output as a nested structure. Use as a starting point for defining a custom PlantUML skin.

PlantUmlSkinParams.java

import com.google.common.collect.ComparisonChain;
import com.google.common.collect.Ordering;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.TreeSet;
import net.sourceforge.plantuml.SkinParam;

/**
 * Dump skinparams skeleton so stdout
 */
public class PlantUmlSkinParams {

    public static void main(String[] args) {
        Collection<String> params = SkinParam.getPossibleValues();
        Param root = new Param("root", -1);
        for (String param : params) {
            List<String> tokens = tokenize(param);
            Param current = root;
            for (int i = 0; i < tokens.size(); i++) {
                String token = tokens.get(i);
                current = current.add(token, i);
            }
        }
        System.out.println(root.toString());
    }

    static List<String> tokenize(String param) {
        ArrayList<String> tokens = new ArrayList<>();
        int start = 0;
        char current;
        for (int i = 1; i < param.length(); i++) {
            current = param.charAt(i);
            if (Character.isUpperCase(current)) {
                tokens.add(param.substring(start, i));
                start = i;
            }
        }
        tokens.add(param.substring(start));

        return tokens;
    }

    static class Param {

        final String name;
        final int level;
        HashMap<String, Param> children;

        public Param(String name, int level) {
            this.name = name;
            this.level = level;
        }

        private Param add(String name, int level) {
            if (children == null) {
                children = new HashMap<>();
            }

            Param child = children.get(name);
            if (child == null) {
                child = new Param(name, level);
                children.put(name, child);
            }
            return child;
        }

        @Override
        public String toString() {
            StringBuilder s = new StringBuilder();

            if (level >= 0) {
                s.append('\n');
                if (level == 0) {
                    s.append("skinparam ");
                } else {
                    indent(s);
                }
                s.append(name);
            }

            if (children != null) {
                if (level >= 0) {
                    s.append(' ').append('{');
                }

                TreeSet<Param> sortedChildren = new TreeSet<>(
                        (Param o1, Param o2) -> ComparisonChain.start()
                        .compare(o1.children, o2.children, Ordering.allEqual()
                                .nullsFirst())
                        .compare(o1.name, o2.name)
                        .result());
                sortedChildren.addAll(children.values());
                for (Param value : sortedChildren) {
                    s.append(value);
                }

                if (level >= 0) {
                    s.append('\n');
                    indent(s);
                    s.append('}');
                }
            }

            if (level == 0) {
                s.append('\n');
            }
            return s.toString();
        }

        private void indent(StringBuilder s) {
            for (int i = 0; i < level; i++) {
                s.append("    ");
            }
        }
    }
}