Autocreated java classes with maven JAXB and persistente customization

Question

I'm generating java classes from an XSD schema. I'm using JAXB 2.2.7 with maven.

in the pom.xml i've a profile and i use it when the XSD change. The build action rewrite all the java classes from scratch. This is the pom profile:

<profile>
    <id>CreateClasses</id>
    <build>
      <plugins>
        <plugin>
          <groupId>org.codehaus.mojo</groupId>
          <artifactId>jaxb2-maven-plugin</artifactId>
          <version>2.3</version>
          <executions>
              <execution>
                  <goals>
                      <goal>xjc</goal>
                  </goals>
              </execution>
          </executions>
          <configuration>
              <schemaDirectory>${basedir}/src/main/resources/documentazione</schemaDirectory>
              <packageName>com.bsssrl.datafatturapa</packageName>
              <outputDirectory>${basedir}/src/main/java</outputDirectory>
              <clearOutputDir>true</clearOutputDir>
              <addGeneratedAnnotation>true</addGeneratedAnnotation>
              <locale>it</locale>
              <properties>
                    <property>
                        <name>javax.xml.XMLConstants.ACCESS_EXTERNAL_SCHEMA</name>
                        <value>http,file</value>
                    </property>
                </properties>
              <sources>
                  <source>${basedir}/src/main/resources/documentazione/fatturapa_v1.2.xsd</source>
              </sources>
          </configuration>
        </plugin>
      </plugins>
    </build>
  </profile>

All the system works well.

Problem: I add some annotations and some methods to the generated classes, for instance some validators and annotations for GUI. If I run the build with the profile CreateClasses because there are some updates on the schema, I loose all the edits.

Question 1 : does exist a way to set a specific Java Class as locked so the system not regenerate this classes?

Question 2 : does exist a way to update a class and not recreate it from blank? Supposing I've 20 properties, now the schema add the 21th one, i don't want to lose my edit to the unchanged properties.