In ggcorr, why are 0s replaced with NA? about ggally HOT 1 OPEN

#m <- data.frame(m * lower.tri(m))
  # replace above with this: 
  m[upper.tri(m, diag = T)] <- NA
  rownames(m) <- colnames(m)
  
  # need to make it a dataframe:
  m <- data.frame(m)
  m$.ggally_ggcorr_row_names <- rownames(m)
  # m = reshape::melt(m, id.vars = ".ggally_ggcorr_row_names")
  # names(m) = c("x", "y", "coefficient")
  m_long <- m %>%
    tidyr::pivot_longer(
      cols = -.ggally_ggcorr_row_names,
      names_to = "y",
      values_to = "coefficient"
    ) %>%
    dplyr::rename(x = .ggally_ggcorr_row_names) %>%
    dplyr::mutate(y = factor(y, levels = rownames(m)))
  
  #m_long$coefficient[m_long$coefficient == 0] <- NA