Program: 34210
Project: 34210
Buggy source:
@SuppressWarnings({"String_Node_Str","String_Node_Str"}) private void mergeAndConvert(ResponseBuilder rb){
  IndexSchema schema=rb.req.getCore().getLatestSchema();
  ReturnFields rf=rb.rsp.getReturnFields();
  boolean wantsShards=rb.req.getParams().getBool(getName() + "String_Node_Str" + SHARD_INFO_PARAM,false);
  SolrDocumentList docs=(SolrDocumentList)rb.rsp.getValues().get("String_Node_Str");
  for (  SolrDocument parent : docs) {
    parent.remove(DuplicateDocumentList.MERGE_PARENT_FIELD);
    Set shardList=wantsShards ? new HashSet() : null;
    Float score=null;
    for (    SolrDocument doc : parent.getChildDocuments()) {
      String shard=(String)doc.getFieldValue("String_Node_Str");
      NamedList nl=null;
      if (shardList != null) {
        nl=new NamedList();
        nl.add("String_Node_Str",shard);
        shardList.add(nl);
      }
      for (      String fieldName : doc.getFieldNames()) {
        Object value=doc.getFieldValue(fieldName);
        for (        CopyField cf : schema.getCopyFieldsList(fieldName)) {
          SchemaField field=cf.getDestination();
          addConvertedFieldValue(shard,parent,value,field);
        }
        SchemaField field=schema.getFieldOrNull(fieldName);
        if (field == null) {
        }
 else         if (field.getName().equals("String_Node_Str")) {
          score=Math.max(score != null ? score : 0.0f,(Float)value);
          if (nl != null) {
            nl.add("String_Node_Str",score);
          }
        }
 else {
          addConvertedFieldValue(shard,parent,value,field);
        }
      }
    }
    if (shardList != null) {
      parent.setField("String_Node_Str",shardList);
    }
 else {
      parent.removeFields("String_Node_Str");
    }
    if (score != null) {
      parent.setField("String_Node_Str",score);
    }
 else {
      parent.removeFields("String_Node_Str");
    }
    for (    SchemaField field : schema.getFields().values()) {
      Object value=parent.getFieldValue(field.getName());
      if (value == null) {
        value=field.getDefaultValue();
        if (value != null) {
          parent.setField(field.getName(),value);
        }
      }
      if (value == null && field.isRequired() && rf.wantsField(field.getName())) {
        throw new MergeException.MissingRequiredField(field);
      }
      if (!field.stored()) {
        parent.removeFields(field.getName());
      }
    }
    while (parent.getChildDocumentCount() > 0) {
      parent.getChildDocuments().remove(0);
    }
  }
}

Fixed version (ground truth):
@SuppressWarnings({"String_Node_Str","String_Node_Str"}) private void mergeAndConvert(ResponseBuilder rb){
  IndexSchema schema=rb.req.getCore().getLatestSchema();
  ReturnFields rf=rb.rsp.getReturnFields();
  SolrDocumentList docs=(SolrDocumentList)rb.rsp.getValues().get("String_Node_Str");
  for (  SolrDocument parent : docs) {
    parent.remove(DuplicateDocumentList.MERGE_PARENT_FIELD);
    Set shardList=new HashSet();
    Float score=null;
    for (    SolrDocument doc : parent.getChildDocuments()) {
      String shard=(String)doc.getFieldValue("String_Node_Str");
      NamedList nl=null;
      if (shard != null) {
        nl=new NamedList();
        nl.add("String_Node_Str",shard);
        shardList.add(nl);
      }
      for (      String fieldName : doc.getFieldNames()) {
        Object value=doc.getFieldValue(fieldName);
        for (        CopyField cf : schema.getCopyFieldsList(fieldName)) {
          SchemaField field=cf.getDestination();
          addConvertedFieldValue(shard,parent,value,field);
        }
        SchemaField field=schema.getFieldOrNull(fieldName);
        if (fieldName.equals("String_Node_Str")) {
          score=Math.max(score != null ? score : 0.0f,(Float)value);
          if (nl != null) {
            nl.add("String_Node_Str",score);
          }
        }
 else         if (field != null) {
          addConvertedFieldValue(shard,parent,value,field);
        }
      }
    }
    if (shardList.size() > 0) {
      parent.setField("String_Node_Str",shardList);
    }
 else {
      parent.removeFields("String_Node_Str");
    }
    if (score != null) {
      parent.setField("String_Node_Str",score);
    }
 else {
      parent.removeFields("String_Node_Str");
    }
    for (    SchemaField field : schema.getFields().values()) {
      Object value=parent.getFieldValue(field.getName());
      if (value == null) {
        value=field.getDefaultValue();
        if (value != null) {
          parent.setField(field.getName(),value);
        }
      }
      if (value == null && field.isRequired() && rf.wantsField(field.getName())) {
        throw new MergeException.MissingRequiredField(field);
      }
      if (!field.stored()) {
        parent.removeFields(field.getName());
      }
    }
    while (parent.getChildDocumentCount() > 0) {
      parent.getChildDocuments().remove(0);
    }
  }
}