if (build != null) {
            List<Plugin> plugins = build.getPlugins();
            Map<Object, Plugin> normalized = new LinkedHashMap<>(plugins.size() * 2);

            for (Plugin plugin : plugins) {
                Object key = plugin.getKey();
                Plugin first = normalized.get(key);
                if (first != null) {
                    plugin = merger.mergePlugin(plugin, first);
                }

  <modelVersion>4.0.0</modelVersion>
  <artifactId>foo</artifactId>
  <groupId>foo</groupId>
  <version>99.44</version>
  <packaging>bleh</packaging>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-it-plugin</artifactId>
      </plugin>
    </plugins>
  </build>

under the License.
-->

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>aid</artifactId>
  <groupId>gid</groupId>
  <version>0.1</version>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-it-plugin</artifactId>
        <version>0.1</version>
        <dependencies>
          <dependency>
            <groupId>test</groupId>
            <artifactId>a</artifactId>

<project>
  <modelVersion>4.0.0</modelVersion>
  <artifactId>foo</artifactId>
  <groupId>foo</groupId>
  <version>99.44</version>
  <packaging>bleh</packaging>
  <build>
    <plugins>
      <plugin>
        <version>1.0</version>
      </plugin>
    </plugins>
  </build>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <executions>
          <execution>
            <id>normal</id>

            <goals>
              <goal>compile</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

/**
 * Maven G level metadata generator.
 * <p>
 * Plugin metadata contains G level list of "prefix" to A mapping for plugins present under this G.
 *
 * @deprecated since 4.0.0, use {@code maven-api-impl} jar instead
 */
@Deprecated(since = "4.0.0")
class PluginsMetadataGenerator implements MetadataGenerator {
    private static final String PLUGIN_DESCRIPTOR_LOCATION = "META-INF/maven/plugin.xml";

  <artifactId>testinvalidpom</artifactId>
  <version>0.0.1-SNAPSHOT</version>

  <build>
    <pluginManagement>
      <plugins>
        <plugin>
          <groupId>the.group.id</groupId>
          <artifactId>the.artifact</artifactId>
          <version/>
        </plugin>
      </plugins>
    </pluginManagement>
  </build>

import org.apache.logging.log4j.core.appender.rewrite.RewritePolicy;
import org.apache.logging.log4j.core.config.plugins.Plugin;
import org.apache.logging.log4j.core.config.plugins.PluginAttribute;
import org.apache.logging.log4j.core.config.plugins.PluginFactory;
import org.apache.logging.log4j.core.impl.Log4jLogEvent;

@Plugin(name = "ErrorToWarnRewritePolicy", category = Core.CATEGORY_NAME, elementType = "rewritePolicy", printObject = true)

      <version>1.0</version>
    </dependency>

  </dependencies>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-antrun-plugin</artifactId>
        <configuration>
          <tasks><echo>${project.parent.basedir}</echo></tasks>
        </configuration>
      </plugin>
    </plugins>
  </build>

      <subscribe>******@****.***</subscribe>
      <unsubscribe>******@****.***</unsubscribe>
    </mailingList-->
  </mailingLists>

  <build>
    <plugins>
      <plugin>
        <groupId>inheritance.configuration</groupId>
        <artifactId>default</artifactId>
        <version>3.0</version>
        <configuration>
          <defaults>
            <parent>child</parent>