Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to 537daa16e66464b4f252c75bcd3171e63835d951
  - SonarFix- MigrateServer.java

    The imports part of a file should be handled by the Integrated Development Environment (IDE), not manually by the developer.
    Unused and useless imports should not occur if that is the case.
    Leaving them in reduces the code's readability, since their presence can be confusing.

    Change-Id: Ic0af785e3d3863f4555ab9614d7a8b3b0f2150b3
    Issue-ID: APPC-1670
    Signed-off-by: anushadasari <danush10@in.ibm.com>

diff --git a/docs/submodules/appc.git b/docs/submodules/appc.git
index f660cb7..537daa1 160000 (submodule)
--- a/docs/submodules/appc.git
+++ b/docs/submodules/appc.git
@@ -1 +1 @@
-Subproject commit f660cb70d74773d414cdf695ca2324f4d6dae48a
+Subproject commit 537daa16e66464b4f252c75bcd3171e63835d951