Use TrustedRequestFactory to make an HTTP POST request without the user password

import com.atlassian.jira.config.IssueTypeManager
import com.atlassian.jira.project.ProjectManager
import com.atlassian.oauth.Request
import com.atlassian.sal.api.ApplicationProperties
import com.atlassian.sal.api.UrlMode
import com.onresolve.scriptrunner.runner.customisers.PluginModule
import groovy.json.JsonOutput
import groovy.json.JsonSlurper

import java.net.http.HttpClient
import java.net.http.HttpRequest
import java.net.http.HttpResponse
import java.nio.charset.StandardCharsets

@PluginModule
ApplicationProperties applicationProperties

@PluginModule
ProjectManager projectManager

@PluginModule
IssueTypeManager issueTypeManager

def project = projectManager.getProjectByCurrentKey('JRA')
def issueType = issueTypeManager.issueTypes.find { it.name == 'Bug' }

def url = applicationProperties.getBaseUrl(UrlMode.CANONICAL) + '/rest/api/2/issue'

def requestBody = JsonOutput.toJson([
    fields: [
        project: [
            id: project.id
        ],
        issuetype: [
            id: issueType.id
        ],
        summary: 'build me a rocket',
    ]
])

def request = HttpRequest.newBuilder()
    .uri(OAuthRequestSigner.createOAuthUri(url))
    .header("Content-Type", "application/json")
    .header("Authorization", OAuthRequestSigner.createAuthorizationHeader(url, Request.HttpMethod.POST))
    .POST(HttpRequest.BodyPublishers.ofString(requestBody, StandardCharsets.UTF_8))
    .build()

def response = HttpClient.newHttpClient()
    .send(request, HttpResponse.BodyHandlers.ofString())

if (response.statusCode() >= 400) {
    throw new Exception("Status code: ${response.statusCode()}. Response body: ${response.body()}")
}

def issueAsMap = new JsonSlurper().parseText(response.body()) as Map

issueAsMap

/*
   responseBody is a JSON string that looks like:

  {
    "id": "10030",
    "key": "JRA-8",
    "self": "http://localhost:8080/jira/rest/api/2/issue/10030"
  }

 */