Fix NullPointerException when convernt the result from Object to Boolean

The request result object would not be assigned value if mAdnCache is null.
The nullpointerexception occurred when the null request result is converted from Object type to Boolean type.
Return false directly if the result object is null.

Bug: 155032134
Test: manual
Change-Id: Ieaaaa6006671ec0292fa988369e7a7d9ea8ae609