build.gradle

plugins {
	id 'fabric-loom' version '0.4-SNAPSHOT'
	id 'maven-publish'
}

sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8

archivesBaseName = project.archives_base_name
version = project.mod_version
group = project.maven_group

dependencies {
	//to change the versions see the gradle.properties file
	minecraft "com.mojang:minecraft:${project.minecraft_version}"
	mappings "net.fabricmc:yarn:${project.yarn_mappings}:v2"
	modImplementation "net.fabricmc:fabric-loader:${project.loader_version}"

	// Fabric API. This is technically optional, but you probably want it anyway.
	modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"

//	modImplementation "io.github.cottonmc:LibGui:1.7.0+1.15.2"
	modImplementation "io.github.cottonmc:LibGui:+"

	// PSA: Some older mods, compiled on Loom 0.2.1, might have outdated Maven POMs.
	// You may need to force-disable transitiveness on them.

	// Utilities for messing with JVM bytecode from https://asm.ow2.io/index.html
//	implementation "org.ow2.asm.asm-all:+"
}

processResources {
	inputs.property "version", project.version

	from(sourceSets.main.resources.srcDirs) {
		include "fabric.mod.json"
		expand "version": project.version
	}

	from(sourceSets.main.resources.srcDirs) {
		exclude "fabric.mod.json"
	}
}

// ensure that the encoding is set to UTF-8, no matter what the system default is
// this fixes some edge cases with special characters not displaying correctly
// see http://yodaconditions.net/blog/fix-for-java-file-encoding-problems-with-gradle.html
tasks.withType(JavaCompile) {
	options.encoding = "UTF-8"
}

// Loom will automatically attach sourcesJar to a RemapSourcesJar task and to the "build" task
// if it is present.
// If you remove this task, sources will not be generated.
task sourcesJar(type: Jar, dependsOn: classes) {
	classifier = "sources"
	from sourceSets.main.allSource
}

jar {
	from "LICENSE"
}

// configure the maven publication
publishing {
	publications {
		mavenJava(MavenPublication) {
			// add all the jars that should be included when publishing to maven
			artifact(remapJar) {
				builtBy remapJar
			}
			artifact(sourcesJar) {
				builtBy remapSourcesJar
			}
		}
	}

	// select the repositories you want to publish to
	repositories {
		// uncomment to publish to the local maven
		// mavenLocal()
	}
}

gradle.properties

# Done to increase the memory available to gradle.
org.gradle.jvmargs=-Xmx1G

# Fabric Properties
	# check these on https://fabricmc.net/use
	minecraft_version=1.15.2
	yarn_mappings=1.15.2+build.17
	loader_version=0.8.7+build.201

# Mod Properties
	mod_version = 0.0.1
	maven_group = com.eliotlash.stormlight
	archives_base_name = stormlight

# Dependencies
	# currently not on the main fabric site, check on the maven: https://maven.fabricmc.net/net/fabricmc/fabric-api/fabric-api
	fabric_version=0.11.1+build.312-1.15

OUTPUT.txt

A problem occurred configuring root project 'fabric-example-mod'.
> Could not resolve all dependencies for configuration ':modImplementation'.
   > Could not find any matches for io.github.cottonmc:LibGui:+ as no versions of io.github.cottonmc:LibGui are available.
     Searched in the following locations:
       - https://libraries.minecraft.net/io/github/cottonmc/LibGui/maven-metadata.xml
       - file:/Users/eliot/Dev/eliot/minecraft/fabric/fabric-example-mod/build/loom-cache/
       - file:/Users/eliot/Dev/eliot/minecraft/fabric/fabric-example-mod/.gradle/loom-cache/remapped_mods/
       - https://maven.fabricmc.net/io/github/cottonmc/LibGui/maven-metadata.xml
       - https://repo.maven.apache.org/maven2/io/github/cottonmc/LibGui/maven-metadata.xml
       - https://jcenter.bintray.com/io/github/cottonmc/LibGui/maven-metadata.xml
       - file:/Users/eliot/.gradle/caches/fabric-loom/1.15.2-mapped-net.fabricmc.yarn-1.15.2+build.17-v2/
     Required by:
         project :

Possible solution:
 - Declare repository providing the artifact, see the documentation at https://docs.gradle.org/current/userguide/declaring_repositories.html

settings.gradle

pluginManagement {
    repositories {
        jcenter()
        maven {
            name = 'Fabric'
            url = 'https://maven.fabricmc.net/'
        }
        maven {
            name = 'OW2'
            url = 'https://repository.ow2.org/'
        }
        maven {
            name = "CottonMC"
            url = "https://server.bbkr.space/artifactory/libs-release"
        }
        gradlePluginPortal()
    }
}