* Returns {@code true} if the value has been partially collected, meaning that the value is
     * null.
     */
    static <K, V, E extends InternalEntry<K, V, E>> boolean isCollected(E entry) {
      return entry.getValue() == null;
    }

    /**
     * Gets the value from an entry. Returns {@code null} if the entry is invalid or
     * partially-collected.
     */
    @Nullable V getLiveValue(E entry) {

     * their source, but the next messages will use the new source.
     *
     * @param source a source
     */
    void setSource(String source);

    /**
     *
     * @return the collected Problems, never {@code null}
     */
    List<Problem> getProblems();

    List<ArtifactRepository> getPluginArtifactRepositories();

    /**
     * Sets the system properties to use for interpolation and profile activation. The system properties are collected
     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @param systemProperties The system properties, may be {@code null}.

    void flush();

    /**
     * Registers the specified cache record for usage with the given project. Integrators can use the information
     * collected from this method in combination with a custom cache implementation to dispose unused records from the
     * cache.
     *
     * @param project The project that employs the plugin realm, must not be {@code null}.

import com.google.common.cache.CacheLoader.UnsupportedLoadingOperationException;
import com.google.common.collect.AbstractSequentialIterator;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Maps;
import com.google.common.primitives.Ints;
import com.google.common.util.concurrent.ExecutionError;

            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++;
            } else if (!holder.closed && holder.getAge() > maxResourceAge * 2) {

#   none    - Disable caching entirely
#
# REFERENCE OPTIONS:
#   hard - Strong reference (stays in memory, faster access)
#   soft - Weak reference (can be garbage collected under memory pressure)
#
# CONFIGURATION BREAKDOWN:
#   SourceCacheKey                   - File and RAW model requests (session/hard for consistent file access)

    void flush();

    /**
     * Registers the specified cache record for usage with the given project. Integrators can use the information
     * collected from this method in combination with a custom cache implementation to dispose unused records from the
     * cache.
     *
     * @param project The project that employs the plugin realm, must not be {@code null}.

import static com.google.common.cache.LocalCache.Strength.STRONG;
import static com.google.common.collect.Maps.immutableEntry;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.base.Function;
import com.google.common.cache.LocalCache.Strength;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import java.lang.ref.WeakReference;
import junit.framework.TestCase;

     */
    List<String> getInactiveProfileIds();

    /**
     * Gets the system properties to use for interpolation and profile activation. The system properties are collected
     * from the runtime environment like {@link System#getProperties()} and environment variables.
     *
     * @return The execution properties, never {@code null}.
     */
    Map<String, String> getSystemProperties();