Generating event logs from a graph for process mining

Graph.java

package graph;

import java.util.*;
import com.google.common.collect.*;

/**
 * @author Alexey Grigorev
 */
public class Graph {

    private static final int MAX_VISITS = 2;

    private final Multimap<String, String> nodes = HashMultimap.create();
    private final Set<String> end = Sets.newHashSet();

    public void addEdge(String from, String to) {
        nodes.put(from, to);
    }

    public void setEndPoints(String... ends) {
        end.addAll(Arrays.asList(ends));
    }

    public Iterable<String> adjacent(String node) {
        return nodes.get(node);
    }

    public List<String> explore(String first) {
        List<String> result = Lists.newLinkedList();

        Queue<History> q = Lists.newLinkedList();
        q.add(new History(first));

        while (!q.isEmpty()) {
            History next = q.poll();
            String vertex = next.node;

            if (end.contains(vertex)) {
                result.add(next.path);
                continue;
            }

            for (String u : adjacent(vertex)) {
                if (next.good(u)) {
                    q.add(next.cont(u));
                }
            }
        }
        return result;
    }

    private static class History {
        private final String node;
        private final String path;
        private final Multiset<String> visited;

        public History(String node, String path, Multiset<String> visited) {
            this.node = node;
            this.path = path;
            this.visited = visited;
        }

        public History(String node) {
            this(node, node, HashMultiset.<String> create());
        }

        public boolean good(String next) {
            return visited.count(next) < MAX_VISITS;
        }

        public History cont(String next) {
            HashMultiset<String> copy = HashMultiset.create(visited);
            copy.add(next);
            return new History(next, path + ' ' + next, copy);
        }

        @Override
        public String toString() {
            return "History [node=" + node + ", path=" + path + "]";
        }
    }
}

GraphTest.java

package graph;

import java.util.List;
import org.junit.Test;

/**
 * @author Alexey Grigorev
 */
public class GraphTest {

    @Test
    public void test() {
        Graph g = new Graph();

        g.addEdge("A", "B");
        g.addEdge("B", "C");
        g.addEdge("C", "D");
        g.addEdge("D", "F");
        g.addEdge("D", "X");
        g.addEdge("F", "B");
        g.addEdge("C", "E");
        g.addEdge("E", "GH");
        g.addEdge("E", "HG");
        g.addEdge("GH", "J");
        g.addEdge("HG", "J");
        g.addEdge("J", "K");
        g.addEdge("K", "N");
        g.addEdge("N", "R");
        g.addEdge("N", "K");
        g.addEdge("K", "L");
        g.addEdge("K", "M");
        g.addEdge("M", "L");
        g.addEdge("L", "O");
        g.addEdge("O", "P");
        g.addEdge("P", "K");
        g.addEdge("P", "R");
        g.addEdge("M", "Q");
        g.addEdge("Q", "Z");
        g.addEdge("R", "S");
        g.addEdge("S", "R");
        g.addEdge("S", "K");
        g.addEdge("R", "T");
        g.addEdge("T", "W");
        g.addEdge("W", "T");
        g.addEdge("T", "Y");
        g.addEdge("Y", "Z");

        g.setEndPoints("X", "Z");

        List<String> res = g.explore("A");

        for (String path : res) {
            System.out.println(path);
        }
    }

}

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>it4bi.ulb.bpm</groupId>
  <artifactId>sec-gen</artifactId>
  <version>0.0.1-SNAPSHOT</version>

  <dependencies>
    <dependency>
      <groupId>com.google.guava</groupId>
      <artifactId>guava</artifactId>
      <version>15.0</version>
    </dependency>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit-dep</artifactId>
      <version>4.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.0</version>
        <configuration>
          <source>1.7</source>
          <target>1.7</target>
        </configuration>
      </plugin>
    </plugins>
  </build>
</project>