master branch, solr indexer fails with a message that I don't understand

[kaveh minooie]

I am using master branch, solr is version 6 and in cloud configuration. 
I am using 'cloud' for solr.server.type in nutch-site.xml.

does this make sense to anybody?
16/05/23 13:52:27 INFO mapreduce.Job:  map 100% reduce 100%
16/05/23 13:52:27 INFO mapreduce.Job: Task Id : 
attempt_1462499602101_0119_r_000000_0, Status : FAILED
Error: Bad return type
Exception Details:
  Location:

org/apache/solr/client/solrj/impl/HttpClientUtil.createClient(Lorg/apache/solr/common/params/SolrParams;Lorg/apache/http/conn/ClientConnectionManager;)Lorg/apache/http/impl/client/CloseableHttpClient; 
@58: areturn
  Reason:
    Type 'org/apache/http/impl/client/DefaultHttpClient' (current 
frame, stack[0]) is not assignable to 
'org/apache/http/impl/client/CloseableHttpClient' (from method signature)
  Current Frame:
    bci: @58
    flags: { }
    locals: { 'org/apache/solr/common/params/SolrParams', 
'org/apache/http/conn/ClientConnectionManager', 
'org/apache/solr/common/params/ModifiableSolrParams', 
'org/apache/http/impl/client/DefaultHttpClient' }
    stack: { 'org/apache/http/impl/client/DefaultHttpClient' }
  Bytecode:
    0x0000000: bb00 0359 2ab7 0004 4db2 0005 b900 0601
    0x0000010: 0099 001e b200 05bb 0007 59b7 0008 1209
    0x0000020: b600 0a2c b600 0bb6 000c b900 0d02 002b
    0x0000030: b800 104e 2d2c b800 0f2d b0
  Stackmap Table:
    append_frame(@47,Object[#143])

16/05/23 13:52:28 INFO mapreduce.Job:  map 100% reduce 0%



--
Kaveh Minooie