If you feel lost with all these **"regular expression"** ideas, don't worry. They are a hard topic for many people. You can still do a lot of stuff without needing regular expressions yet.

Now you know that whenever you need them you can use them in **FastAPI**.

## Default values { #default-values }

You can, of course, use default values other than `None`.

func (p *JSONPool[T]) NewJSONWith(val *T) *JSON[T] {
	var j JSON[T]
	j.p = p
	j.val = val
	return &j
}

// Value returns the underlying value.
// If not set yet, a new value is created.
func (j *JSON[T]) Value() *T {
	if j.val == nil {
		j.val = j.p.new()
	}
	return j.val
}

// ValueOrZero returns the underlying value.

/**
 * An implementation of a workspace reader that knows how to search the Maven reactor for artifacts, either as packaged
 * jar if it has been built, or only compile output directory if packaging hasn't happened yet.
 *
 */
@Named(ReactorReader.HINT)
@SessionScoped
class ReactorReader implements MavenWorkspaceReader {
    public static final String HINT = "reactor";

    // Lock while we check state. We must maintain the lock while adding the new pair so that
    // another thread can't run the list out from under us. We only add to the list if we have not
    // yet started execution.
    synchronized (lock) {
      if (!executed) {
        runnables = new RunnableExecutorPair(runnable, executor, runnables);
        return;
      }
    }

    </executions>
  </plugin>
  .
  .
  .
</plugins>

We need this form so that the model builder can make the first pass at merging. Full merging cannot be done because we don't know what the version of the plugin is yet that the user has requested. For plugins in the default lifecycle they are typically defined in the plugin management section of the parent POM. When the merging is complete we are going to have something that looks like the following:

/*
 * This script plugin configures formatting for Java source using Spotless
 * for Gradle. Since the act of formatting existing source can interfere
 * with developers' workflows, we don't automatically format all code
 * (yet). Instead, we maintain a list of projects that are excluded from
 * formatting, until we reach a point where we can comfortably format them
 * in one go without too much disruption.
 *

   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.
   *   <li>null, if no entries have yet been added to the map
   * </ul>
   */
  private transient @Nullable Object table;

  /**
   * Contains the logical entries, in the range of [0, size()). The high bits of each int are the

        assertTrue(resp.isLoggedInAsGuest(), "Anonymous should be treated as guest login");
    }

    @Test
    @DisplayName("prepare should not set sessionId if not received yet")
    void testPrepareWithoutReceivedDoesNotPropagate() {
        Smb2SessionSetupResponse resp = newResponse();
        // Set a sessionId, but do not mark as received via decode
        resp.setSessionId(0x1234L);

    def someClusterProvider = testClusters.register('someCluster') { ... }

This registers a potential testCluster named `somecluster` and provides a provider instance, but doesn't create it yet nor configures it. This makes the gradle configuration phase more efficient by 
doing less.

   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.
   *   <li>null, if no entries have yet been added to the map
   * </ul>
   */
  private transient @Nullable Object table;

  /**
   * Contains the logical entries, in the range of [0, size()). The high bits of each int are the