# ADR-0008 - Use NullAway for null checking

## Date

2025-08-06

## Context

Our codebase uses `null` extensively to represent an absence of value or optionality of the argument.
We utilize nullness annotations in Java code and somewhat rely on IDE warnings to guide us.
However, the Java code we have is not fully annotated, which causes several consequences:
* IDE warnings can be misleading

        // Test presence of flags
        assertTrue((flags & SecurityInfo.OWNER_SECURITY_INFO) != 0);
        assertTrue((flags & SecurityInfo.DACL_SECURITY_INFO) != 0);

        // Test absence of flags
        assertTrue((flags & SecurityInfo.GROUP_SECURITY_INFO) == 0);
        assertTrue((flags & SecurityInfo.SACL_SECURITY_INFO) == 0);
    }

    @Test
    @DisplayName("Test interface extends Decodable")

    assertEquals("message", record.getMessage());
    assertSame(EXCEPTION, record.getThrown());
  }

  public void testConcurrentModification() throws Exception {
    // Tests for the absence of a bug where logging while iterating over the
    // stored log records causes a ConcurrentModificationException
    assertTrue(handler.getStoredLogRecords().isEmpty());
    ExampleClassUnderTest.foo();

import org.codehaus.plexus.interpolation.InterpolationException;
import org.codehaus.plexus.util.StringUtils;

/**
 * Determines profile activation based on the existence/absence of some file.
 * File name interpolation support is limited to <code>${project.basedir}</code>
 * system properties and user properties.
 *
 * @see ActivationFile

  }

  /** Equivalent to {@code add(-1)}. */
  public void decrement() {
    add(-1L);
  }

  /**
   * Returns the current sum. The returned value is NOT an atomic snapshot; invocation in
   * the absence of concurrent updates returns an accurate result, but concurrent updates that occur
   * while the sum is being calculated might not be incorporated.
   *
   * @return the sum
   */
  @Override
  public long sum() {

  }

  /** Equivalent to {@code add(-1)}. */
  public void decrement() {
    add(-1L);
  }

  /**
   * Returns the current sum. The returned value is NOT an atomic snapshot; invocation in
   * the absence of concurrent updates returns an accurate result, but concurrent updates that occur
   * while the sum is being calculated might not be incorporated.
   *
   * @return the sum
   */
  @Override
  public long sum() {

     * fail. Use a custom [HostnameVerifier] to ignore such problems.
     *
     * Other TLS features are still used but provide no security benefits in absence of the above
     * gaps. For example, an insecure TLS connection is capable of negotiating HTTP/2 with ALPN and
     * it also has a regular-looking handshake.
     *

   * AbstractListTester isn't enough because many tests that run on lists don't
   * extends AbstractListTester.) We could also iterate over all elements to
   * verify absence
   */
  protected void expectMissing(E... elements) {
    for (E element : elements) {
      assertFalse("Should not contain " + element, actualContents().contains(element));
    }
  }

 * a traditional {@code HashMap} implementation which stores keys and count values as map entries,
 * {@code ObjectCountHashMap} minimizes object allocation and reduces memory footprint.
 *
 * <p>In the absence of element deletions, this will iterate over elements in insertion order.
 */
@GwtCompatible
@NullMarked
class ObjectCountHashMap<K extends @Nullable Object> {

  types of tests cannot be setup, since the container used to run them cannot be
  reached or started.

  All of these operations will produce their own unique errors in the absence of
  a coordinated offline strategy. In addition, efforts to unite these failing
  behaviors behind a consistent user interface is much, much more difficult if