Changed .javacp creation timing.

- Changed .javacp creation timing from generate-sources -> compile.
  It was causing unnecessary classpath scanning during javadoc:javadoc, etc.

Change-Id: Id88714e4e7194170f6adc13cecaedef17ac6e376
diff --git a/pom.xml b/pom.xml
index 32a7a99..6840723 100644
--- a/pom.xml
+++ b/pom.xml
@@ -238,7 +238,7 @@
         <executions>
           <execution>
             <id>build-classpath</id>
-            <phase>generate-sources</phase>
+            <phase>compile</phase>
             <goals>
               <goal>build-classpath</goal>
             </goals>