RFC7950Reactors.defaultReactor can not build the yang file with content "yang-version 1.0"

In my project, I'm trying to parse the yang files with yangtools parser, and RFC7950Reactors.defaultReactor is chosen as below:

CrossSourceStatementReactor.BuildAction reactor = RFC7950Reactors.defaultReactor().newBuild();

addSourceFiles(reactor, compatibleDir);

SchemaContext schemaContext= reactor.buildEffective();

Then I test the yang files in compatibleDir, if the yang file is specified with "yang-version 1.0", I'll get the Exception below:

org.opendaylight.yangtools.yang.parser.spi.meta.SomeModifiersUnresolvedException: Some of FULL_DECLARATION modifiers for statements were not resolved.
org.opendaylight.yangtools.yang.parser.stmt.reactor.BuildGlobalContext.propagateException(BuildGlobalContext.java:256)
org.opendaylight.yangtools.yang.parser.stmt.reactor.BuildGlobalContext.loadPhaseStatementsFor(BuildGlobalContext.java:310)
org.opendaylight.yangtools.yang.parser.stmt.reactor.BuildGlobalContext.loadPhaseStatements(BuildGlobalContext.java:300)
org.opendaylight.yangtools.yang.parser.stmt.reactor.BuildGlobalContext.executePhases(BuildGlobalContext.java:218)
org.opendaylight.yangtools.yang.parser.stmt.reactor.BuildGlobalContext.buildEffective(BuildGlobalContext.java:230)

And if I remove the content "yang-version 1.0" or replace it with "yang-version 1.1", I'll get the yang file parsed correctly, no exceptions occured.

Can anyone help with the issue I encountered.Thacks.