*/
    Map<String, String> getSystemProperties();

    /**
     * Gets the user properties to use for interpolation and profile activation. The user properties have been
     * configured directly by the user on his discretion, e.g. via the {@code -Dkey=value} parameter on the command
     * line.
     *
     * @return The user properties, never {@code null}.
     */

You can change/extend these stubs, and tests should not be breaking too much, since most tests
assert using expected values from the stubs. Normally, when you try to use data from the stubs that
have not been properly populated, you'll get a nullpointer in your test and you then have to
identify which stub creates that specific piece of data.

The most important stubs are:
LifecycleExecutionPlanCalculatorStub

            ResourceHolder holder = entry.getValue();

            // Check if resource is abandoned
            if (!holder.closed && !holder.isAlive()) {
                // Resource object has been garbage collected but not closed
                reportLeak(holder);
                activeResources.remove(entry.getKey());
                cleaned++;

package com.google.common.math;

import com.google.common.testing.AbstractPackageSanityTests;
import org.jspecify.annotations.NullUnmarked;

/**
 * Basic sanity tests for the entire package.
 *
 * @author Ben Yu
 */

@NullUnmarked
public class PackageSanityTests extends AbstractPackageSanityTests {
  public PackageSanityTests() {
    publicApiOnly();
  }

       */
      boolean unused = addCausalChain(seen, requireNonNull(tryInternalFastPathGetFailure()));
    }
  }

  /**
   * Collects the result (success or failure) of one input future. The input must not have been
   * cancelled. For details on when this is called, see {@link #collectOneValue}.
   */
  private void collectValueFromNonCancelledFuture(int index, Future<? extends InputT> future) {
    try {

  }

  Stopwatch(Ticker ticker) {
    this.ticker = checkNotNull(ticker, "ticker");
  }

  /**
   * Returns {@code true} if {@link #start()} has been called on this stopwatch, and {@link #stop()}
   * has not been called since the last call to {@code start()}.
   */
  public boolean isRunning() {
    return isRunning;
  }

  /**
   * Starts the stopwatch.
   *

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			sr.fillReady <- int64(n)
		}
	}()

	sr.fillReq <- struct{}{} // initial fill

	return sr
}

// remaining returns the number of unread bytes
// if EOF for the underlying reader has not yet been found,
// maximum possible integer value will be returned
func (s *scanner) remaining() int64 {
	if atomic.LoadInt64(&s.end) == maxInt {
		return maxInt
	}
	return atomic.LoadInt64(&s.end) - s.pos
}

     *
     * @param responseData the response data from the crawled resource
     * @param resultData the result data to be processed
     * @return the processed result data after all ingesters have been applied
     */
    private ResultData ingest(final ResponseData responseData, final ResultData resultData) {
        if (ingestFactory == null) {
            return resultData;
        }

package com.google.common.primitives;

import com.google.common.testing.AbstractPackageSanityTests;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests basic sanity for each class in the package.
 *
 * @author Ben Yu
 */

@NullUnmarked
public class PackageSanityTests extends AbstractPackageSanityTests {
  public PackageSanityTests() {
    setDefault(String.class, "string");
  }