In many cases your application could need some external settings or configurations, for example secret keys, database credentials, credentials for email services, etc.

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

/// tip

 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSortedMap} forward <i>indiscriminately</i> to
 * the methods of the delegate. For example, overriding {@link #put} alone <i>will not</i> change
 * the behavior of {@link #putAll}, which can lead to unexpected behavior. In this case, you should
 * override {@code putAll} as well, either providing your own implementation, or delegating to the

  }

  public void testBuildMutate() {
    ThreadFactory factory1 = builder.setPriority(1).build();
    assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());

    builder.setPriority(2); // change the state of the builder
    assertEquals(1, factory1.newThread(monitoredRunnable).getPriority());
  }

  public void testThreadFactory() throws InterruptedException {
    String THREAD_NAME = "ludicrous speed";

     */
    public void setDeprecated(String deprecated) {
        this.deprecated = deprecated;
    }

    /**
     * @return the list of parameters copy. Any change to returned list is NOT reflected on this instance. To add
     * parameters, use {@link #addParameter(Parameter)} method.
     */
    public List<Parameter> getParameters() {
        return new ArrayList<>(parameters);

   * at a time, but since read operations and cache loading computations can proceed concurrently,
   * this still yields higher concurrency than full synchronization.
   *
   * <p>Defaults to 4. <b>Note:</b>The default may change in the future. If you care about this
   * value, you should always choose it explicitly.
   *
   * <p>The current implementation uses the concurrency level to create a fixed number of hashtable

import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Multimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableMultimap} as a type (as with

import java.util.function.Function;
import java.util.function.ToIntFunction;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Multiset} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Grouped iteration.</b> In all current implementations, duplicate elements always appear

       * pass.
       *
       * 2. We would probably choose to compare exceptions using == instead of equals() (for
       * consistency with how weak references are cleared). That's a behavior change -- arguably the
       * removal of a feature.
       *
       * Fortunately, exceptions rarely contain references to expensive resources.
       */

      //
      seenExceptionsLocal = newConcurrentHashSet();

 * {@link #enqueue} and {@link #dispatch} are 2 different methods. It is expected that the decision
 * to run a particular event is made during the state change, but the decision to actually invoke
 * the listeners can be delayed slightly so that locks can be dropped. Also, because {@link
 * #dispatch} is expected to be called concurrently, it is idempotent.
 */
@J2ktIncompatible

   */
  public static List<String> readLines(URL url, Charset charset) throws IOException {
    // don't use asCharSource(url, charset).readLines() because that returns
    // an immutable list, which would change the behavior of this method
    return readLines(
        url,
        charset,
        new LineProcessor<List<String>>() {
          final List<String> result = new ArrayList<>();

          @Override