* should override one or more methods to modify the behavior of the backing future as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingListenableFuture} forward
 * <b>indiscriminately</b> to the methods of the delegate. For example, overriding {@link #get(long,

package org.apache.maven;

import org.apache.maven.execution.MavenSession;

/**
 * Allows core extensions to participate in Maven build session lifecycle.
 *
 * All callback methods (will) follow beforeXXX/afterXXX naming pattern to
 * indicate at what lifecycle point it is being called.
 *
 * @see <a href="https://maven.apache.org/examples/maven-3-lifecycle-extensions.html">example</a>

 * more methods to modify the behavior of the backing deque as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingDeque} forward <b>indiscriminately</b> to the
 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the

 * methods to modify the behavior of the backing set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSet} forward <b>indiscriminately</b> to the
 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the

 * methods to modify the behavior of the backing set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingSet} forward <b>indiscriminately</b> to the
 * methods of the delegate. For example, overriding {@link #add} alone <b>will not</b> change the

        // global-level settings somewhere other than ${user.home} and ${maven.home},
        // respectively. Using a simple replacement of these patterns will allow them
        // to specify the absolute path to these files in a customized components.xml
        // file. Ideally, we'd do full pattern-evaluation against the sysprops, but this
        // is a first step. There are several replacements below, in order to normalize

 * override one or more methods to modify the behavior of the backing sorted map as desired per the
 * <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <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

 * one or more methods to modify the behavior of the backing multimap as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations

 * one or more methods to modify the behavior of the backing multimap as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *
 * <p><b>{@code default} method warning:</b> This class does <i>not</i> forward calls to {@code
 * default} methods. Instead, it inherits their default implementations. When those implementations

* Some public APIs have incorrect nullability annotations (both overly restrictive and overly permissive)

While there are competing ways to represent absence (`Optional`, "Null Object" pattern, method overloads),
it is unlikely that we'll be able to remove `null` entirely.

After migrating to Java 8, we can use pluggable type checkers to ensure that our annotations are consistent, 
and there are no missing null checks.