Explain on query missing overridden property values

[big-andy-coates]

To Reproduce

-- override a property:
SET 'ksql.streams.num.stream.threads'='2';

-- create a MV:
CREATE STREAM FOO (ID INT) WITH (KAFKA_TOPIC='FOO', PARTITIONS=1,VALUE_FORMAT='json');
CREATE STREAM BAR AS SELECT * FROM FOO;

-- explain the query created in the step above:
EXPLAIN CSAS_BAR_0;

Expected behavior

...

Overridden Properties
---------------------
 Property                        | Value 

 ksql.streams.num.stream.threads | 2     

Actual behaviour

...

Overridden Properties
---------------------
 Property                        | Value 

 ksql.streams.num.stream.threads | 

i.e. the value for the overridden property is missing