private Synchronized() {}

  private static class SynchronizedObject implements Serializable {
    final Object delegate;
    final Object mutex;

    SynchronizedObject(Object delegate, @Nullable Object mutex) {
      this.delegate = checkNotNull(delegate);
      this.mutex = (mutex == null) ? this : mutex;
    }

    Object delegate() {
      return delegate;
    }

    // No equals and hashCode; see ForwardingObject for details.

# Run static analysis
mvn spotbugs:check
```

### Running Tests

```bash
# Run all tests
mvn test

# Run specific test class
mvn test -Dtest=CrawlerTest

# Run specific test method
mvn test -Dtest=CrawlerTest#test_execute_web

# Run tests for specific module
mvn test -pl fess-crawler
```

## Examples

### Web Crawling with Custom Rules

```java

      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override
    public E remove() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove();
    }

    @Override
    public boolean remove(Object object) {
      assertTrue(Thread.holdsLock(mutex));

      return delegate.offer(o);
    }

    @Override
    public @Nullable E poll() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.poll();
    }

    @Override
    public E remove() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.remove();
    }

    @Override
    public boolean remove(Object object) {
      assertTrue(Thread.holdsLock(mutex));

      checkNotNull(mutex);
      this.delegate = delegate;
      this.mutex = mutex;
    }

    @Override
    protected Map<K, V> delegate() {
      return delegate;
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return super.size();
    }

    @Override
    public boolean isEmpty() {
      assertTrue(Thread.holdsLock(mutex));

    private final Object mutex = new Object[0]; // something Serializable

    @Override
    public String toString() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.toString();
    }

    @Override
    public boolean equals(@Nullable Object o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.equals(o);
    }

    @Override

  final Set<E> delegate;
  final Object mutex;

  LockHeldAssertingSet(Set<E> delegate, Object mutex) {
    checkNotNull(mutex);
    this.delegate = delegate;
    this.mutex = mutex;
  }

  @Override
  protected Set<E> delegate() {
    return delegate;
  }

  @Override
  public String toString() {
    assertTrue(Thread.holdsLock(mutex));
    return super.toString();
  }

  @Override

pkg testing, type InternalFuzzTarget struct, Name string
pkg text/template/parse, const NodeBreak = 21
pkg text/template/parse, const NodeBreak NodeType
pkg text/template/parse, const NodeContinue = 22
pkg text/template/parse, const NodeContinue NodeType
pkg text/template/parse, method (*BreakNode) Copy() Node
pkg text/template/parse, method (*BreakNode) String() string
pkg text/template/parse, method (*ContinueNode) Copy() Node

      checkNotNull(mutex);
      this.delegate = delegate;
      this.mutex = mutex;
    }

    @Override
    protected Map<K, V> delegate() {
      return delegate;
    }

    @Override
    public int size() {
      assertTrue(Thread.holdsLock(mutex));
      return super.size();
    }

    @Override
    public boolean isEmpty() {
      assertTrue(Thread.holdsLock(mutex));

    private final Object mutex = new Object[0]; // something Serializable

    @Override
    public String toString() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.toString();
    }

    @Override
    public boolean equals(@Nullable Object o) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.equals(o);
    }

    @Override