Customdata in texttemplate could not be found in heatmap

For a heatmap chart I want to create a hyperlink, which is provided in the customdata. For some reason it looks like the customdata fields is not accessible from the texttemplate field. Executing the sample code below with browser debug mode shows that customdata is not found:

import plotly.graph_objects as go
labels = ["a", "b", "c"]
z = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
customdata = [["http://google.com", "http://google.com", "http://google.com"], ["http://google.com", "http://google.com", "http://google.com"], ["http://google.com", "http://google.com", "http://google.com"]]
fig = go.Figure(data=go.Heatmap(x=labels, y=labels,
                                z=z,
                                customdata=customdata,
                                texttemplate="""<a href="%{customdata}">%{z}</a>""",
                                hovertemplate='%{customdata}<extra></extra>',
                                textfont={"size": 20}))
fig.show()

從提供的 Python heatmap 範例開始，追蹤 Heatmap customdata 如何傳遞給 texttemplate，並將其與正常運作的 hovertemplate 行為進行比較。透過使用 customdata URL 渲染超連結，並檢查現有的 hover 文字是否仍能正確顯示，確認 fix。