SourceFormatter prevent ConcurrentModificationException

format-source:
     [java] java.util.ConcurrentModificationException
     [java] 	at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793)
     [java] 	at java.util.HashMap$EntryIterator.next(HashMap.java:834)
     [java] 	at java.util.HashMap$EntryIterator.next(HashMap.java:832)
     [java] 	at com.liferay.portal.tools.sourceformatter.BaseSourceProcessor.fixCompatClassImports(BaseSourceProcessor.java:381)
     [java] 	at com.liferay.portal.tools.sourceformatter.JavaSourceProcessor.format(JavaSourceProcessor.java:879)
     [java] 	at com.liferay.portal.tools.sourceformatter.JavaSourceProcessor.format(JavaSourceProcessor.java:789)
     [java] 	at com.liferay.portal.tools.sourceformatter.BaseSourceProcessor.format(BaseSourceProcessor.java:65)
     [java] 	at com.liferay.portal.tools.sourceformatter.SourceFormatter$1.run(SourceFormatter.java:76)