tree d3624e105490d5f51dd1df6d762a07d8e1b1a918
parent 51d0c40ad6c9181a172fb1fc14aa8d39b66e7ba7
author Patrick Venture <venture@google.com> 1565977818 -0700
committer Patrick Venture <venture@google.com> 1566316501 -0700

entitymap: add json parsing support

Add a json parsing method that given an entity map in the format:
[
  {
     "id" : 1,
     "containerEntityId" : 2,
     "containerEntityInstance" : 3,
     "isList" : false,
     "isLinked" : false,
     "entities" : [
         {"id" : 1, "instance" : 2},
         {"id" : 1, "instance" : 3},
         {"id" : 1, "instance" : 4},
         {"id" : 1, "instance" : 5}
     ]
  }
]

is constructed into the entity map used by sensorhandler.  This is meant
as part of the transition from the entity map in YAML to JSON.

This is step 2.  Step 1 moved access to the object behind a method.
This adds JSON validation and parsing.  Step 3 will add a file path to
check and parse.  Step 4 will provide a call to parse that file if
present and use its data if non-empty.

Tested: The method added has not been tested beyond unit-test validation.
Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Ic29f022d3812fa9e3af775d542ad055629fd5a01