app = FastAPI()


@app.get("/catching")
def catching(d: Annotated[str, Depends(catching_dep)]) -> Any:
    raise CustomError("Simulated error during streaming")


@app.get("/broken")
def broken(d: Annotated[str, Depends(broken_dep)]) -> Any:
    return {"message": "all good?"}


client = TestClient(app)


def test_catching():
    response = client.get("/catching")
    assert response.status_code == 418

  public void testCatching() throws Exception {
    FluentFuture<?> f =
        FluentFuture.from(immediateFailedFuture(new CustomRuntimeException()))
            .catching(
                Throwable.class,
                new Function<Throwable, Class<?>>() {
                  @Override
                  public Class<?> apply(Throwable input) {
                    return input.getClass();

 * {@link #transform(ClosingFunction, Executor)} or {@link #transformAsync(AsyncClosingFunction,
 * Executor)} on the input step.
 *
 * <h4>Catching</h4>
 *
 * To derive the next step from a failed input step, call {@link #catching(Class, ClosingFunction,
 * Executor)} or {@link #catchingAsync(Class, AsyncClosingFunction, Executor)} on the input step.
 *
 * <h4>Combining</h4>
 *

## Verify the `username` and data shape { #verify-the-username-and-data-shape }

We verify that we get a `username`, and extract the scopes.

And then we validate that data with the Pydantic model (catching the `ValidationError` exception), and if we get an error reading the JWT token or validating the data with Pydantic, we raise the `HTTPException` we created before.

    // same value. below comes before above
    return Boolean.compare(this instanceof AboveValue, that instanceof AboveValue);
  }

  C endpoint() {
    return endpoint;
  }

  @SuppressWarnings("unchecked") // catching CCE
  @Override
  public boolean equals(@Nullable Object obj) {
    if (obj instanceof Cut) {
      // It might not really be a Cut<C>, but we'll catch a CCE if it's not
      Cut<C> that = (Cut<C>) obj;
      try {

    // same value. below comes before above
    return Boolean.compare(this instanceof AboveValue, that instanceof AboveValue);
  }

  C endpoint() {
    return endpoint;
  }

  @SuppressWarnings("unchecked") // catching CCE
  @Override
  public boolean equals(@Nullable Object obj) {
    if (obj instanceof Cut) {
      // It might not really be a Cut<C>, but we'll catch a CCE if it's not
      Cut<C> that = (Cut<C>) obj;
      try {

_2025-07-07_

 *  New: `Response.peekTrailers()`. When we changed `Response.trailers()` to block instead of
    throwing in 5.0.0, we inadvertently removed the ability for callers to peek the trailers
    (by catching the `IllegalStateException` if they weren't available). This new API restores that
    capability.

 *  Fix: Don't crash on `trailers()` if the response doesn't have a body. We broke [Retrofit] users

    keyEquivalence = builder.getKeyEquivalence();
    this.entryHelper = entryHelper;

    int initialCapacity = min(builder.getInitialCapacity(), MAXIMUM_CAPACITY);

    // Find power-of-two sizes best matching arguments. Constraints:
    // (segmentCount > concurrencyLevel)
    int segmentShift = 0;
    int segmentCount = 1;
    while (segmentCount < concurrencyLevel) {
      ++segmentShift;
      segmentCount <<= 1;

       * elements from each bin must either stay at same index, or move with a power of two offset.
       * We eliminate unnecessary node creation by catching cases where old nodes can be reused
       * because their next fields won't change. Statistically, at the default threshold, only about

- **Exception Handling** (`org.codelibs.core.exception`) - Runtime exception wrappers for common checked exceptions with consistent error handling

### Modern Java 21 Support
- **Pattern Matching** - Leverages modern Java pattern matching for efficient type checking and conversion
- **Switch Expressions** - Optimized implementations using switch expressions for better performance