code: @POST
      @Consumes(Servlets.JSON_MEDIA_TYPE)
      @Produces(Servlets.JSON_MEDIA_TYPE)
      public AtlasRelationship create(AtlasRelationship relationship) throws AtlasBaseException {
          AtlasPerfTracer perf = null;
  
          try {
              if (AtlasPerfTracer.isPerfTraceEnabled(PERF_LOG)) {
                  perf = AtlasPerfTracer.getPerfTracer(PERF_LOG, "RelationshipREST.create(" + relationship + ")");
              }
  
              return relationshipStore.create(relationship);
  
          } finally {
              AtlasPerfTracer.log(perf);
          }
      }
docs: Create a new relationship between entities.