code: public void setSourceSegments(java.util.Collection<SegmentReference> sourceSegments) {
          if (sourceSegments == null) {
              this.sourceSegments = null;
              return;
          }
  
          this.sourceSegments = new java.util.ArrayList<SegmentReference>(sourceSegments);
      }
docs: The base segment that you build your segment on. The source segment defines the starting "universe" of endpoints.
  When you add dimensions to the segment, it filters the source segment based on the dimensions that you specify.
  You can specify more than one dimensional segment. You can only specify one imported segment.
  
  NOTE: If you specify an imported segment for this attribute, the segment size estimate that appears in the Amazon
  Pinpoint console shows the size of the imported segment, without any filters applied to it.
  
  @param sourceSegments
  The base segment that you build your segment on. The source segment defines the starting "universe" of
  endpoints. When you add dimensions to the segment, it filters the source segment based on the dimensions
  that you specify. You can specify more than one dimensional segment. You can only specify one imported
  segment.
  
  NOTE: If you specify an imported segment for this attribute, the segment size estimate that appears in the
  Amazon Pinpoint console shows the size of the imported segment, without any filters applied to it.