See full tutorial here : https://cedricleruth.com/how-to-configure-jdeveloper-to-trust-an-ssl-certificate-and-fix-pkix-path-building-failed-when-connecting-to-an-https-url/

ConfigureJdeveloperToTrustAnSSLCertificate.bash

# This kind of error when calling an https url in Jdeveloper
# means that you need to add it's SSL certificate to Jdeveloper trusted keystore :
# sun.security.validator.ValidatorException: PKIX path building failed:sun.security.provider.certpath.SunCertPathBuilderException: 
# unable to find validcertification path to requested target

# To fix this : 
# 1) Download the SSL certificate from the https url.
#   1.a) go to the url
#   1.b) click on the padlock next to the url in your web browser
#   1.c) click the certificate button
#   1.d) Navigate to the detail tab
#   1.e) Click on copy to file to download a .crt file
# 2) open a cmd prompt (Windows > cmd) and run this command (1 line)
#   Note : Don't forget to put your values instead of YOUR_JAVA_JDK_BIN_FOLDER YOUR_SSL_CERTIFICATE_FOLDER YOUR_CERTIFICATE_NAME YOUR_MIDDLEWARE_INSTALL_FOLDER
#   YOUR_JAVA_JDK_BIN_FOLDER (e.g: C:\Program Files\Java\jdk1.8.0\bin\)

"YOUR_JAVA_JDK_BIN_FOLDER\keytool.exe" -import -trustcacerts -file "YOUR_SSL_CERTIFICATE_FOLDER\YOUR_CERTIFICATE_NAME.crt"   -alias YOUR_CERTIFICATE_NAME   -keystore "YOUR_MIDDLEWARE_INSTALL_FOLDER\wlserver\server\lib\DemoTrust.jks"
#   If you use the DemoTrust.jks provided by default the password is : DemoTrustKeyStorePassPhrase

# 3) Restart your Jdeveloper