Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to c48d6919b00989e0927b503c16f8ca12464cf367
  - Code block added to avoid Null pointer Exception
    
    Added condition to avoid NullPointer Exception
    
    Issue-ID: APPC-1425
    Change-Id: I166633ccfcf51a8fcc8d4082aa8d2afa4b299398
    Signed-off-by: Jegadeesh Babu <jegabab1@in.ibm.com>
    
diff --git a/docs/submodules/appc.git b/docs/submodules/appc.git
index a2e8379..c48d691 160000
--- a/docs/submodules/appc.git
+++ b/docs/submodules/appc.git
@@ -1 +1 @@
-Subproject commit a2e8379525676bf48ef13e3ed953c836aa37dd07
+Subproject commit c48d6919b00989e0927b503c16f8ca12464cf367