writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidRequestParameter), r.URL)
		return
	} else if checksumType.IsSet() && !checksumType.Is(hash.ChecksumTrailing) {
		opts.WantChecksum = &hash.Checksum{Type: checksumType}
	}

	newMultipartUpload := objectAPI.NewMultipartUpload

	res, err := newMultipartUpload(ctx, bucket, object, opts)
	if err != nil {

Without a data validation system, you would have to do all the checks by hand, in code.

These features are what Marshmallow was built to provide. It is a great library, and I have used it a lot before.

import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.regex.Pattern;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit test for {@link Doubles}.
 *
 * @author Kevin Bourrillion
 */
@ElementTypesAreNonnullByDefault
@GwtCompatible(emulated = true)
public class DoublesTest extends TestCase {

import java.util.Set;
import java.util.concurrent.Callable;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import org.checkerframework.checker.nullness.qual.Nullable;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

/**
 * Abstract base class for testing implementations of {@link Network} interface. Network instances

import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.function.BinaryOperator;
import java.util.stream.Collector;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Provides static methods that involve a {@code Table}.
 *
 * <p>See the Guava User Guide article on <a href=

import java.nio.charset.Charset;
import java.util.Iterator;
import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Stream;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A readable source of characters, such as a text file. Unlike a {@link Reader}, a {@code
 * CharSource} is not an open, stateful stream of characters that can be read and closed. Instead,

import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ConcurrentMap;
import junit.framework.Assert;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A test utility that verifies that your methods and constructors throw {@link
 * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.FutureTask;
import java.util.concurrent.TimeUnit;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Generated tests for {@link Monitor}.
 *
 * <p>This test class generates all of its own test cases in the {@link #suite()} method. Every

import java.util.Map.Entry;
import java.util.function.BiPredicate;
import java.util.stream.Collector;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Tests for {@link ImmutableListMultimap}.
 *
 * @author Jared Levy
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault

	if err != nil {
		return nil, err
	}
	parsedFileCache[filename] = f

	return f, nil
}

// Disable before debugging non-obvious errors from the type-checker.
const usePkgCache = true

var (
	pkgCache = map[string]*apiPackage{} // map tagKey to package
	pkgTags  = map[string][]string{}    // map import dir to list of relevant tags
)