Receiving an error during compilation Error: execution completed for task ': packageAllDebugClassesForMultiDex'

Question

After adding the com.google.gdata:core:1.47.1gradle dependency , a build error now constantly occurs.

Error:Execution failed for task ':packageAllDebugClassesForMultiDex'.
> java.util.zip.ZipException: duplicate entry: com/google/gdata/util/common/base/UnicodeEscaper$1.class

I excluded most of the dependencies on com.google.gdata:core:1.47.1, here is the gradle code.

compile('com.google.gdata:core:1.47.1') {
        exclude(group: 'javax.mail', module: 'mail')
        exclude(group: 'com.google.oauth-client', module: 'google-oauth-client-jetty')
    }

After googling search my project has 2 jars (signpost-core-1.2.1.1.jar & com.google.gdata:core:1.47.1)that have one common package (com.google.gdata.util.common.base). This creates a problem that I think of. I tried to exclude the general package, but no luck.